Calculus Examples

Find the Inflection Points f(x)=cx^2-5x^-2
Step 1
Find the second derivative.
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Step 1.1
Find the first derivative.
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Step 1.1.1
By the Sum Rule, the derivative of with respect to is .
Step 1.1.2
Evaluate .
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Step 1.1.2.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.2.2
Differentiate using the Power Rule which states that is where .
Step 1.1.2.3
Move to the left of .
Step 1.1.3
Evaluate .
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Step 1.1.3.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.3.2
Differentiate using the Power Rule which states that is where .
Step 1.1.3.3
Multiply by .
Step 1.1.4
Simplify.
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Step 1.1.4.1
Rewrite the expression using the negative exponent rule .
Step 1.1.4.2
Combine and .
Step 1.2
Find the second derivative.
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Step 1.2.1
By the Sum Rule, the derivative of with respect to is .
Step 1.2.2
Evaluate .
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Step 1.2.2.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.2.2.2
Differentiate using the Power Rule which states that is where .
Step 1.2.2.3
Multiply by .
Step 1.2.3
Evaluate .
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Step 1.2.3.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.2.3.2
Rewrite as .
Step 1.2.3.3
Differentiate using the chain rule, which states that is where and .
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Step 1.2.3.3.1
To apply the Chain Rule, set as .
Step 1.2.3.3.2
Differentiate using the Power Rule which states that is where .
Step 1.2.3.3.3
Replace all occurrences of with .
Step 1.2.3.4
Differentiate using the Power Rule which states that is where .
Step 1.2.3.5
Multiply the exponents in .
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Step 1.2.3.5.1
Apply the power rule and multiply exponents, .
Step 1.2.3.5.2
Multiply by .
Step 1.2.3.6
Multiply by .
Step 1.2.3.7
Multiply by by adding the exponents.
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Step 1.2.3.7.1
Move .
Step 1.2.3.7.2
Use the power rule to combine exponents.
Step 1.2.3.7.3
Subtract from .
Step 1.2.3.8
Multiply by .
Step 1.2.4
Simplify.
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Step 1.2.4.1
Rewrite the expression using the negative exponent rule .
Step 1.2.4.2
Combine terms.
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Step 1.2.4.2.1
Combine and .
Step 1.2.4.2.2
Move the negative in front of the fraction.
Step 1.3
The second derivative of with respect to is .
Step 2
Set the second derivative equal to then solve the equation .
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Step 2.1
Set the second derivative equal to .
Step 2.2
Subtract from both sides of the equation.
Step 2.3
Find the LCD of the terms in the equation.
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Step 2.3.1
Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.
Step 2.3.2
The LCM of one and any expression is the expression.
Step 2.4
Multiply each term in by to eliminate the fractions.
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Step 2.4.1
Multiply each term in by .
Step 2.4.2
Simplify the left side.
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Step 2.4.2.1
Cancel the common factor of .
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Step 2.4.2.1.1
Move the leading negative in into the numerator.
Step 2.4.2.1.2
Cancel the common factor.
Step 2.4.2.1.3
Rewrite the expression.
Step 2.5
Solve the equation.
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Step 2.5.1
Rewrite the equation as .
Step 2.5.2
Divide each term in by and simplify.
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Step 2.5.2.1
Divide each term in by .
Step 2.5.2.2
Simplify the left side.
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Step 2.5.2.2.1
Cancel the common factor of .
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Step 2.5.2.2.1.1
Cancel the common factor.
Step 2.5.2.2.1.2
Rewrite the expression.
Step 2.5.2.2.2
Cancel the common factor of .
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Step 2.5.2.2.2.1
Cancel the common factor.
Step 2.5.2.2.2.2
Divide by .
Step 2.5.2.3
Simplify the right side.
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Step 2.5.2.3.1
Cancel the common factor of and .
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Step 2.5.2.3.1.1
Factor out of .
Step 2.5.2.3.1.2
Cancel the common factors.
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Step 2.5.2.3.1.2.1
Factor out of .
Step 2.5.2.3.1.2.2
Cancel the common factor.
Step 2.5.2.3.1.2.3
Rewrite the expression.
Step 2.5.3
Take the specified root of both sides of the equation to eliminate the exponent on the left side.
Step 2.5.4
Simplify .
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Step 2.5.4.1
Rewrite as .
Step 2.5.4.2
Multiply by .
Step 2.5.4.3
Combine and simplify the denominator.
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Step 2.5.4.3.1
Multiply by .
Step 2.5.4.3.2
Raise to the power of .
Step 2.5.4.3.3
Use the power rule to combine exponents.
Step 2.5.4.3.4
Add and .
Step 2.5.4.3.5
Rewrite as .
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Step 2.5.4.3.5.1
Use to rewrite as .
Step 2.5.4.3.5.2
Apply the power rule and multiply exponents, .
Step 2.5.4.3.5.3
Combine and .
Step 2.5.4.3.5.4
Cancel the common factor of .
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Step 2.5.4.3.5.4.1
Cancel the common factor.
Step 2.5.4.3.5.4.2
Rewrite the expression.
Step 2.5.4.3.5.5
Simplify.
Step 2.5.4.4
Rewrite as .
Step 2.5.4.5
Combine using the product rule for radicals.
Step 2.5.5
The complete solution is the result of both the positive and negative portions of the solution.
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Step 2.5.5.1
First, use the positive value of the to find the first solution.
Step 2.5.5.2
Next, use the negative value of the to find the second solution.
Step 2.5.5.3
The complete solution is the result of both the positive and negative portions of the solution.
Step 3
Find the points where the second derivative is .
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Step 3.1
Substitute in to find the value of .
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Step 3.1.1
Replace the variable with in the expression.
Step 3.1.2
Simplify the result.
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Step 3.1.2.1
Simplify each term.
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Step 3.1.2.1.1
Apply the product rule to .
Step 3.1.2.1.2
Simplify the numerator.
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Step 3.1.2.1.2.1
Rewrite as .
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Step 3.1.2.1.2.1.1
Use to rewrite as .
Step 3.1.2.1.2.1.2
Apply the power rule and multiply exponents, .
Step 3.1.2.1.2.1.3
Combine and .
Step 3.1.2.1.2.1.4
Cancel the common factor of and .
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Step 3.1.2.1.2.1.4.1
Factor out of .
Step 3.1.2.1.2.1.4.2
Cancel the common factors.
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Step 3.1.2.1.2.1.4.2.1
Factor out of .
Step 3.1.2.1.2.1.4.2.2
Cancel the common factor.
Step 3.1.2.1.2.1.4.2.3
Rewrite the expression.
Step 3.1.2.1.2.1.5
Rewrite as .
Step 3.1.2.1.2.2
Rewrite as .
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Step 3.1.2.1.2.2.1
Factor out .
Step 3.1.2.1.2.2.2
Reorder and .
Step 3.1.2.1.2.2.3
Add parentheses.
Step 3.1.2.1.2.3
Pull terms out from under the radical.
Step 3.1.2.1.3
Cancel the common factor of .
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Step 3.1.2.1.3.1
Factor out of .
Step 3.1.2.1.3.2
Cancel the common factor.
Step 3.1.2.1.3.3
Rewrite the expression.
Step 3.1.2.1.4
Cancel the common factor of .
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Step 3.1.2.1.4.1
Cancel the common factor.
Step 3.1.2.1.4.2
Divide by .
Step 3.1.2.1.5
Change the sign of the exponent by rewriting the base as its reciprocal.
Step 3.1.2.1.6
Multiply by .
Step 3.1.2.1.7
Combine and simplify the denominator.
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Step 3.1.2.1.7.1
Multiply by .
Step 3.1.2.1.7.2
Raise to the power of .
Step 3.1.2.1.7.3
Use the power rule to combine exponents.
Step 3.1.2.1.7.4
Add and .
Step 3.1.2.1.7.5
Rewrite as .
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Step 3.1.2.1.7.5.1
Use to rewrite as .
Step 3.1.2.1.7.5.2
Apply the power rule and multiply exponents, .
Step 3.1.2.1.7.5.3
Combine and .
Step 3.1.2.1.7.5.4
Cancel the common factor of .
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Step 3.1.2.1.7.5.4.1
Cancel the common factor.
Step 3.1.2.1.7.5.4.2
Rewrite the expression.
Step 3.1.2.1.7.5.5
Simplify.
Step 3.1.2.1.8
Cancel the common factor of and .
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Step 3.1.2.1.8.1
Factor out of .
Step 3.1.2.1.8.2
Cancel the common factors.
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Step 3.1.2.1.8.2.1
Factor out of .
Step 3.1.2.1.8.2.2
Cancel the common factor.
Step 3.1.2.1.8.2.3
Rewrite the expression.
Step 3.1.2.1.9
Simplify the numerator.
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Step 3.1.2.1.9.1
Rewrite as .
Step 3.1.2.1.9.2
Apply the product rule to .
Step 3.1.2.1.9.3
Raise to the power of .
Step 3.1.2.1.9.4
Multiply the exponents in .
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Step 3.1.2.1.9.4.1
Apply the power rule and multiply exponents, .
Step 3.1.2.1.9.4.2
Multiply by .
Step 3.1.2.1.9.5
Rewrite as .
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Step 3.1.2.1.9.5.1
Factor out .
Step 3.1.2.1.9.5.2
Rewrite as .
Step 3.1.2.1.9.5.3
Reorder and .
Step 3.1.2.1.9.5.4
Add parentheses.
Step 3.1.2.1.9.6
Pull terms out from under the radical.
Step 3.1.2.1.10
Cancel the common factor of .
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Step 3.1.2.1.10.1
Cancel the common factor.
Step 3.1.2.1.10.2
Rewrite the expression.
Step 3.1.2.1.11
Apply the product rule to .
Step 3.1.2.1.12
Simplify the numerator.
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Step 3.1.2.1.12.1
Rewrite as .
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Step 3.1.2.1.12.1.1
Use to rewrite as .
Step 3.1.2.1.12.1.2
Apply the power rule and multiply exponents, .
Step 3.1.2.1.12.1.3
Combine and .
Step 3.1.2.1.12.1.4
Cancel the common factor of and .
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Step 3.1.2.1.12.1.4.1
Factor out of .
Step 3.1.2.1.12.1.4.2
Cancel the common factors.
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Step 3.1.2.1.12.1.4.2.1
Factor out of .
Step 3.1.2.1.12.1.4.2.2
Cancel the common factor.
Step 3.1.2.1.12.1.4.2.3
Rewrite the expression.
Step 3.1.2.1.12.1.5
Rewrite as .
Step 3.1.2.1.12.2
Rewrite as .
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Step 3.1.2.1.12.2.1
Factor out of .
Step 3.1.2.1.12.2.2
Rewrite as .
Step 3.1.2.1.12.2.3
Add parentheses.
Step 3.1.2.1.12.3
Pull terms out from under the radical.
Step 3.1.2.1.13
Raise to the power of .
Step 3.1.2.1.14
Cancel the common factor of .
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Step 3.1.2.1.14.1
Factor out of .
Step 3.1.2.1.14.2
Factor out of .
Step 3.1.2.1.14.3
Cancel the common factor.
Step 3.1.2.1.14.4
Rewrite the expression.
Step 3.1.2.1.15
Cancel the common factor of and .
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Step 3.1.2.1.15.1
Factor out of .
Step 3.1.2.1.15.2
Cancel the common factors.
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Step 3.1.2.1.15.2.1
Factor out of .
Step 3.1.2.1.15.2.2
Cancel the common factor.
Step 3.1.2.1.15.2.3
Rewrite the expression.
Step 3.1.2.1.16
Rewrite as .
Step 3.1.2.2
To write as a fraction with a common denominator, multiply by .
Step 3.1.2.3
Simplify terms.
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Step 3.1.2.3.1
Combine and .
Step 3.1.2.3.2
Combine the numerators over the common denominator.
Step 3.1.2.4
Simplify the numerator.
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Step 3.1.2.4.1
Move to the left of .
Step 3.1.2.4.2
Subtract from .
Step 3.1.2.5
The final answer is .
Step 3.2
The point found by substituting in is . This point can be an inflection point.
Step 3.3
Substitute in to find the value of .
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Step 3.3.1
Replace the variable with in the expression.
Step 3.3.2
Simplify the result.
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Step 3.3.2.1
Simplify each term.
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Step 3.3.2.1.1
Use the power rule to distribute the exponent.
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Step 3.3.2.1.1.1
Apply the product rule to .
Step 3.3.2.1.1.2
Apply the product rule to .
Step 3.3.2.1.2
Rewrite using the commutative property of multiplication.
Step 3.3.2.1.3
Cancel the common factor of .
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Step 3.3.2.1.3.1
Factor out of .
Step 3.3.2.1.3.2
Factor out of .
Step 3.3.2.1.3.3
Cancel the common factor.
Step 3.3.2.1.3.4
Rewrite the expression.
Step 3.3.2.1.4
Combine and .
Step 3.3.2.1.5
Simplify the numerator.
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Step 3.3.2.1.5.1
Raise to the power of .
Step 3.3.2.1.5.2
Rewrite as .
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Step 3.3.2.1.5.2.1
Use to rewrite as .
Step 3.3.2.1.5.2.2
Apply the power rule and multiply exponents, .
Step 3.3.2.1.5.2.3
Combine and .
Step 3.3.2.1.5.2.4
Cancel the common factor of and .
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Step 3.3.2.1.5.2.4.1
Factor out of .
Step 3.3.2.1.5.2.4.2
Cancel the common factors.
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Step 3.3.2.1.5.2.4.2.1
Factor out of .
Step 3.3.2.1.5.2.4.2.2
Cancel the common factor.
Step 3.3.2.1.5.2.4.2.3
Rewrite the expression.
Step 3.3.2.1.5.2.5
Rewrite as .
Step 3.3.2.1.5.3
Rewrite as .
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Step 3.3.2.1.5.3.1
Factor out .
Step 3.3.2.1.5.3.2
Reorder and .
Step 3.3.2.1.5.3.3
Add parentheses.
Step 3.3.2.1.5.4
Pull terms out from under the radical.
Step 3.3.2.1.5.5
Multiply by .
Step 3.3.2.1.6
Cancel the common factor of .
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Step 3.3.2.1.6.1
Cancel the common factor.
Step 3.3.2.1.6.2
Divide by .
Step 3.3.2.1.7
Change the sign of the exponent by rewriting the base as its reciprocal.
Step 3.3.2.1.8
Multiply by .
Step 3.3.2.1.9
Combine and simplify the denominator.
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Step 3.3.2.1.9.1
Multiply by .
Step 3.3.2.1.9.2
Raise to the power of .
Step 3.3.2.1.9.3
Use the power rule to combine exponents.
Step 3.3.2.1.9.4
Add and .
Step 3.3.2.1.9.5
Rewrite as .
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Step 3.3.2.1.9.5.1
Use to rewrite as .
Step 3.3.2.1.9.5.2
Apply the power rule and multiply exponents, .
Step 3.3.2.1.9.5.3
Combine and .
Step 3.3.2.1.9.5.4
Cancel the common factor of .
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Step 3.3.2.1.9.5.4.1
Cancel the common factor.
Step 3.3.2.1.9.5.4.2
Rewrite the expression.
Step 3.3.2.1.9.5.5
Simplify.
Step 3.3.2.1.10
Cancel the common factor of and .
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Step 3.3.2.1.10.1
Factor out of .
Step 3.3.2.1.10.2
Cancel the common factors.
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Step 3.3.2.1.10.2.1
Factor out of .
Step 3.3.2.1.10.2.2
Cancel the common factor.
Step 3.3.2.1.10.2.3
Rewrite the expression.
Step 3.3.2.1.11
Simplify the numerator.
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Step 3.3.2.1.11.1
Rewrite as .
Step 3.3.2.1.11.2
Apply the product rule to .
Step 3.3.2.1.11.3
Raise to the power of .
Step 3.3.2.1.11.4
Multiply the exponents in .
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Step 3.3.2.1.11.4.1
Apply the power rule and multiply exponents, .
Step 3.3.2.1.11.4.2
Multiply by .
Step 3.3.2.1.11.5
Rewrite as .
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Step 3.3.2.1.11.5.1
Factor out .
Step 3.3.2.1.11.5.2
Rewrite as .
Step 3.3.2.1.11.5.3
Reorder and .
Step 3.3.2.1.11.5.4
Add parentheses.
Step 3.3.2.1.11.6
Pull terms out from under the radical.
Step 3.3.2.1.12
Cancel the common factor of .
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Step 3.3.2.1.12.1
Cancel the common factor.
Step 3.3.2.1.12.2
Rewrite the expression.
Step 3.3.2.1.13
Use the power rule to distribute the exponent.
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Step 3.3.2.1.13.1
Apply the product rule to .
Step 3.3.2.1.13.2
Apply the product rule to .
Step 3.3.2.1.14
Raise to the power of .
Step 3.3.2.1.15
Multiply by .
Step 3.3.2.1.16
Simplify the numerator.
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Step 3.3.2.1.16.1
Rewrite as .
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Step 3.3.2.1.16.1.1
Use to rewrite as .
Step 3.3.2.1.16.1.2
Apply the power rule and multiply exponents, .
Step 3.3.2.1.16.1.3
Combine and .
Step 3.3.2.1.16.1.4
Cancel the common factor of and .
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Step 3.3.2.1.16.1.4.1
Factor out of .
Step 3.3.2.1.16.1.4.2
Cancel the common factors.
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Step 3.3.2.1.16.1.4.2.1
Factor out of .
Step 3.3.2.1.16.1.4.2.2
Cancel the common factor.
Step 3.3.2.1.16.1.4.2.3
Rewrite the expression.
Step 3.3.2.1.16.1.5
Rewrite as .
Step 3.3.2.1.16.2
Rewrite as .
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Step 3.3.2.1.16.2.1
Factor out of .
Step 3.3.2.1.16.2.2
Rewrite as .
Step 3.3.2.1.16.2.3
Add parentheses.
Step 3.3.2.1.16.3
Pull terms out from under the radical.
Step 3.3.2.1.17
Raise to the power of .
Step 3.3.2.1.18
Cancel the common factor of .
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Step 3.3.2.1.18.1
Factor out of .
Step 3.3.2.1.18.2
Factor out of .
Step 3.3.2.1.18.3
Cancel the common factor.
Step 3.3.2.1.18.4
Rewrite the expression.
Step 3.3.2.1.19
Cancel the common factor of and .
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Step 3.3.2.1.19.1
Factor out of .
Step 3.3.2.1.19.2
Cancel the common factors.
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Step 3.3.2.1.19.2.1
Factor out of .
Step 3.3.2.1.19.2.2
Cancel the common factor.
Step 3.3.2.1.19.2.3
Rewrite the expression.
Step 3.3.2.1.20
Rewrite as .
Step 3.3.2.2
To write as a fraction with a common denominator, multiply by .
Step 3.3.2.3
Simplify terms.
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Step 3.3.2.3.1
Combine and .
Step 3.3.2.3.2
Combine the numerators over the common denominator.
Step 3.3.2.4
Simplify the numerator.
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Step 3.3.2.4.1
Move to the left of .
Step 3.3.2.4.2
Subtract from .
Step 3.3.2.5
The final answer is .
Step 3.4
The point found by substituting in is . This point can be an inflection point.
Step 3.5
Determine the points that could be inflection points.
Step 4
Split into intervals around the points that could potentially be inflection points.
Step 5
Substitute a value from the interval into the second derivative to determine if it is increasing or decreasing.
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Step 5.1
Replace the variable with in the expression.
Step 5.2
The final answer is .
Step 5.3
At , the second derivative is . Since this is negative, the second derivative is decreasing on the interval
Decreasing on since
Decreasing on since
Step 6
Substitute a value from the interval into the second derivative to determine if it is increasing or decreasing.
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Step 6.1
Replace the variable with in the expression.
Step 6.2
The final answer is .
Step 6.3
At , the second derivative is . Since this is negative, the second derivative is decreasing on the interval
Decreasing on since
Decreasing on since
Step 7
An inflection point is a point on a curve at which the concavity changes sign from plus to minus or from minus to plus. There are no points on the graph that satisfy these requirements.
No Inflection Points