Calculus Examples

Find the Local Maxima and Minima f(x)=12x^5-75x^4+160x^3-120x^2+4
Step 1
Find the first derivative of the function.
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Step 1.1
By the Sum Rule, the derivative of with respect to is .
Step 1.2
Evaluate .
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Step 1.2.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.2.2
Differentiate using the Power Rule which states that is where .
Step 1.2.3
Multiply by .
Step 1.3
Evaluate .
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Step 1.3.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.3.2
Differentiate using the Power Rule which states that is where .
Step 1.3.3
Multiply by .
Step 1.4
Evaluate .
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Step 1.4.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.4.2
Differentiate using the Power Rule which states that is where .
Step 1.4.3
Multiply by .
Step 1.5
Evaluate .
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Step 1.5.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.5.2
Differentiate using the Power Rule which states that is where .
Step 1.5.3
Multiply by .
Step 1.6
Differentiate using the Constant Rule.
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Step 1.6.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.6.2
Add and .
Step 2
Find the second derivative of the function.
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Step 2.1
By the Sum Rule, the derivative of with respect to is .
Step 2.2
Evaluate .
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Step 2.2.1
Since is constant with respect to , the derivative of with respect to is .
Step 2.2.2
Differentiate using the Power Rule which states that is where .
Step 2.2.3
Multiply by .
Step 2.3
Evaluate .
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Step 2.3.1
Since is constant with respect to , the derivative of with respect to is .
Step 2.3.2
Differentiate using the Power Rule which states that is where .
Step 2.3.3
Multiply by .
Step 2.4
Evaluate .
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Step 2.4.1
Since is constant with respect to , the derivative of with respect to is .
Step 2.4.2
Differentiate using the Power Rule which states that is where .
Step 2.4.3
Multiply by .
Step 2.5
Evaluate .
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Step 2.5.1
Since is constant with respect to , the derivative of with respect to is .
Step 2.5.2
Differentiate using the Power Rule which states that is where .
Step 2.5.3
Multiply by .
Step 3
To find the local maximum and minimum values of the function, set the derivative equal to and solve.
Step 4
Find the first derivative.
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Step 4.1
Find the first derivative.
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Step 4.1.1
By the Sum Rule, the derivative of with respect to is .
Step 4.1.2
Evaluate .
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Step 4.1.2.1
Since is constant with respect to , the derivative of with respect to is .
Step 4.1.2.2
Differentiate using the Power Rule which states that is where .
Step 4.1.2.3
Multiply by .
Step 4.1.3
Evaluate .
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Step 4.1.3.1
Since is constant with respect to , the derivative of with respect to is .
Step 4.1.3.2
Differentiate using the Power Rule which states that is where .
Step 4.1.3.3
Multiply by .
Step 4.1.4
Evaluate .
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Step 4.1.4.1
Since is constant with respect to , the derivative of with respect to is .
Step 4.1.4.2
Differentiate using the Power Rule which states that is where .
Step 4.1.4.3
Multiply by .
Step 4.1.5
Evaluate .
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Step 4.1.5.1
Since is constant with respect to , the derivative of with respect to is .
Step 4.1.5.2
Differentiate using the Power Rule which states that is where .
Step 4.1.5.3
Multiply by .
Step 4.1.6
Differentiate using the Constant Rule.
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Step 4.1.6.1
Since is constant with respect to , the derivative of with respect to is .
Step 4.1.6.2
Add and .
Step 4.2
The first derivative of with respect to is .
Step 5
Set the first derivative equal to then solve the equation .
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Step 5.1
Set the first derivative equal to .
Step 5.2
Factor the left side of the equation.
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Step 5.2.1
Factor out of .
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Step 5.2.1.1
Factor out of .
Step 5.2.1.2
Factor out of .
Step 5.2.1.3
Factor out of .
Step 5.2.1.4
Factor out of .
Step 5.2.1.5
Factor out of .
Step 5.2.1.6
Factor out of .
Step 5.2.1.7
Factor out of .
Step 5.2.2
Factor using the rational roots test.
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Step 5.2.2.1
If a polynomial function has integer coefficients, then every rational zero will have the form where is a factor of the constant and is a factor of the leading coefficient.
Step 5.2.2.2
Find every combination of . These are the possible roots of the polynomial function.
Step 5.2.2.3
Substitute and simplify the expression. In this case, the expression is equal to so is a root of the polynomial.
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Step 5.2.2.3.1
Substitute into the polynomial.
Step 5.2.2.3.2
Raise to the power of .
Step 5.2.2.3.3
Raise to the power of .
Step 5.2.2.3.4
Multiply by .
Step 5.2.2.3.5
Subtract from .
Step 5.2.2.3.6
Multiply by .
Step 5.2.2.3.7
Add and .
Step 5.2.2.3.8
Subtract from .
Step 5.2.2.4
Since is a known root, divide the polynomial by to find the quotient polynomial. This polynomial can then be used to find the remaining roots.
Step 5.2.2.5
Divide by .
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Step 5.2.2.5.1
Set up the polynomials to be divided. If there is not a term for every exponent, insert one with a value of .
--+-
Step 5.2.2.5.2
Divide the highest order term in the dividend by the highest order term in divisor .
--+-
Step 5.2.2.5.3
Multiply the new quotient term by the divisor.
--+-
+-
Step 5.2.2.5.4
The expression needs to be subtracted from the dividend, so change all the signs in
--+-
-+
Step 5.2.2.5.5
After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.
--+-
-+
-
Step 5.2.2.5.6
Pull the next terms from the original dividend down into the current dividend.
--+-
-+
-+
Step 5.2.2.5.7
Divide the highest order term in the dividend by the highest order term in divisor .
-
--+-
-+
-+
Step 5.2.2.5.8
Multiply the new quotient term by the divisor.
-
--+-
-+
-+
-+
Step 5.2.2.5.9
The expression needs to be subtracted from the dividend, so change all the signs in
-
--+-
-+
-+
+-
Step 5.2.2.5.10
After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.
-
--+-
-+
-+
+-
+
Step 5.2.2.5.11
Pull the next terms from the original dividend down into the current dividend.
-
--+-
-+
-+
+-
+-
Step 5.2.2.5.12
Divide the highest order term in the dividend by the highest order term in divisor .
-+
--+-
-+
-+
+-
+-
Step 5.2.2.5.13
Multiply the new quotient term by the divisor.
-+
--+-
-+
-+
+-
+-
+-
Step 5.2.2.5.14
The expression needs to be subtracted from the dividend, so change all the signs in
-+
--+-
-+
-+
+-
+-
-+
Step 5.2.2.5.15
After changing the signs, add the last dividend from the multiplied polynomial to find the new dividend.
-+
--+-
-+
-+
+-
+-
-+
Step 5.2.2.5.16
Since the remander is , the final answer is the quotient.
Step 5.2.2.6
Write as a set of factors.
Step 5.2.3
Factor.
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Step 5.2.3.1
Factor using the perfect square rule.
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Step 5.2.3.1.1
Rewrite as .
Step 5.2.3.1.2
Check that the middle term is two times the product of the numbers being squared in the first term and third term.
Step 5.2.3.1.3
Rewrite the polynomial.
Step 5.2.3.1.4
Factor using the perfect square trinomial rule , where and .
Step 5.2.3.2
Remove unnecessary parentheses.
Step 5.3
If any individual factor on the left side of the equation is equal to , the entire expression will be equal to .
Step 5.4
Set equal to .
Step 5.5
Set equal to and solve for .
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Step 5.5.1
Set equal to .
Step 5.5.2
Add to both sides of the equation.
Step 5.6
Set equal to and solve for .
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Step 5.6.1
Set equal to .
Step 5.6.2
Solve for .
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Step 5.6.2.1
Set the equal to .
Step 5.6.2.2
Add to both sides of the equation.
Step 5.7
The final solution is all the values that make true.
Step 6
Find the values where the derivative is undefined.
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Step 6.1
The domain of the expression is all real numbers except where the expression is undefined. In this case, there is no real number that makes the expression undefined.
Step 7
Critical points to evaluate.
Step 8
Evaluate the second derivative at . If the second derivative is positive, then this is a local minimum. If it is negative, then this is a local maximum.
Step 9
Evaluate the second derivative.
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Step 9.1
Simplify each term.
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Step 9.1.1
Raising to any positive power yields .
Step 9.1.2
Multiply by .
Step 9.1.3
Raising to any positive power yields .
Step 9.1.4
Multiply by .
Step 9.1.5
Multiply by .
Step 9.2
Simplify by adding and subtracting.
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Step 9.2.1
Add and .
Step 9.2.2
Add and .
Step 9.2.3
Subtract from .
Step 10
is a local maximum because the value of the second derivative is negative. This is referred to as the second derivative test.
is a local maximum
Step 11
Find the y-value when .
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Step 11.1
Replace the variable with in the expression.
Step 11.2
Simplify the result.
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Step 11.2.1
Simplify each term.
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Step 11.2.1.1
Raising to any positive power yields .
Step 11.2.1.2
Multiply by .
Step 11.2.1.3
Raising to any positive power yields .
Step 11.2.1.4
Multiply by .
Step 11.2.1.5
Raising to any positive power yields .
Step 11.2.1.6
Multiply by .
Step 11.2.1.7
Raising to any positive power yields .
Step 11.2.1.8
Multiply by .
Step 11.2.2
Simplify by adding numbers.
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Step 11.2.2.1
Add and .
Step 11.2.2.2
Add and .
Step 11.2.2.3
Add and .
Step 11.2.2.4
Add and .
Step 11.2.3
The final answer is .
Step 12
Evaluate the second derivative at . If the second derivative is positive, then this is a local minimum. If it is negative, then this is a local maximum.
Step 13
Evaluate the second derivative.
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Step 13.1
Simplify each term.
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Step 13.1.1
One to any power is one.
Step 13.1.2
Multiply by .
Step 13.1.3
One to any power is one.
Step 13.1.4
Multiply by .
Step 13.1.5
Multiply by .
Step 13.2
Simplify by adding and subtracting.
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Step 13.2.1
Subtract from .
Step 13.2.2
Add and .
Step 13.2.3
Subtract from .
Step 14
is a local minimum because the value of the second derivative is positive. This is referred to as the second derivative test.
is a local minimum
Step 15
Find the y-value when .
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Step 15.1
Replace the variable with in the expression.
Step 15.2
Simplify the result.
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Step 15.2.1
Simplify each term.
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Step 15.2.1.1
One to any power is one.
Step 15.2.1.2
Multiply by .
Step 15.2.1.3
One to any power is one.
Step 15.2.1.4
Multiply by .
Step 15.2.1.5
One to any power is one.
Step 15.2.1.6
Multiply by .
Step 15.2.1.7
One to any power is one.
Step 15.2.1.8
Multiply by .
Step 15.2.2
Simplify by adding and subtracting.
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Step 15.2.2.1
Subtract from .
Step 15.2.2.2
Add and .
Step 15.2.2.3
Subtract from .
Step 15.2.2.4
Add and .
Step 15.2.3
The final answer is .
Step 16
Evaluate the second derivative at . If the second derivative is positive, then this is a local minimum. If it is negative, then this is a local maximum.
Step 17
Evaluate the second derivative.
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Step 17.1
Simplify each term.
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Step 17.1.1
Raise to the power of .
Step 17.1.2
Multiply by .
Step 17.1.3
Raise to the power of .
Step 17.1.4
Multiply by .
Step 17.1.5
Multiply by .
Step 17.2
Simplify by adding and subtracting.
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Step 17.2.1
Subtract from .
Step 17.2.2
Add and .
Step 17.2.3
Subtract from .
Step 18
Since there is at least one point with or undefined second derivative, apply the first derivative test.
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Step 18.1
Split into separate intervals around the values that make the first derivative or undefined.
Step 18.2
Substitute any number, such as , from the interval in the first derivative to check if the result is negative or positive.
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Step 18.2.1
Replace the variable with in the expression.
Step 18.2.2
Simplify the result.
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Step 18.2.2.1
Simplify each term.
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Step 18.2.2.1.1
Raise to the power of .
Step 18.2.2.1.2
Multiply by .
Step 18.2.2.1.3
Raise to the power of .
Step 18.2.2.1.4
Multiply by .
Step 18.2.2.1.5
Raise to the power of .
Step 18.2.2.1.6
Multiply by .
Step 18.2.2.1.7
Multiply by .
Step 18.2.2.2
Simplify by adding numbers.
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Step 18.2.2.2.1
Add and .
Step 18.2.2.2.2
Add and .
Step 18.2.2.2.3
Add and .
Step 18.2.2.3
The final answer is .
Step 18.3
Substitute any number, such as , from the interval in the first derivative to check if the result is negative or positive.
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Step 18.3.1
Replace the variable with in the expression.
Step 18.3.2
Simplify the result.
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Step 18.3.2.1
Simplify each term.
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Step 18.3.2.1.1
Raise to the power of .
Step 18.3.2.1.2
Multiply by .
Step 18.3.2.1.3
Raise to the power of .
Step 18.3.2.1.4
Multiply by .
Step 18.3.2.1.5
Raise to the power of .
Step 18.3.2.1.6
Multiply by .
Step 18.3.2.1.7
Multiply by .
Step 18.3.2.2
Simplify by adding and subtracting.
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Step 18.3.2.2.1
Subtract from .
Step 18.3.2.2.2
Add and .
Step 18.3.2.2.3
Subtract from .
Step 18.3.2.3
The final answer is .
Step 18.4
Substitute any number, such as , from the interval in the first derivative to check if the result is negative or positive.
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Step 18.4.1
Replace the variable with in the expression.
Step 18.4.2
Simplify the result.
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Step 18.4.2.1
Simplify each term.
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Step 18.4.2.1.1
Raise to the power of .
Step 18.4.2.1.2
Multiply by .
Step 18.4.2.1.3
Raise to the power of .
Step 18.4.2.1.4
Multiply by .
Step 18.4.2.1.5
Raise to the power of .
Step 18.4.2.1.6
Multiply by .
Step 18.4.2.1.7
Multiply by .
Step 18.4.2.2
Simplify by adding and subtracting.
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Step 18.4.2.2.1
Subtract from .
Step 18.4.2.2.2
Add and .
Step 18.4.2.2.3
Subtract from .
Step 18.4.2.3
The final answer is .
Step 18.5
Substitute any number, such as , from the interval in the first derivative to check if the result is negative or positive.
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Step 18.5.1
Replace the variable with in the expression.
Step 18.5.2
Simplify the result.
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Step 18.5.2.1
Simplify each term.
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Step 18.5.2.1.1
Raise to the power of .
Step 18.5.2.1.2
Multiply by .
Step 18.5.2.1.3
Raise to the power of .
Step 18.5.2.1.4
Multiply by .
Step 18.5.2.1.5
Raise to the power of .
Step 18.5.2.1.6
Multiply by .
Step 18.5.2.1.7
Multiply by .
Step 18.5.2.2
Simplify by adding and subtracting.
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Step 18.5.2.2.1
Subtract from .
Step 18.5.2.2.2
Add and .
Step 18.5.2.2.3
Subtract from .
Step 18.5.2.3
The final answer is .
Step 18.6
Since the first derivative changed signs from positive to negative around , then is a local maximum.
is a local maximum
Step 18.7
Since the first derivative changed signs from negative to positive around , then is a local minimum.
is a local minimum
Step 18.8
Since the first derivative did not change signs around , this is not a local maximum or minimum.
Not a local maximum or minimum
Step 18.9
These are the local extrema for .
is a local maximum
is a local minimum
is a local maximum
is a local minimum
Step 19