Calculus Examples

Find the Local Maxima and Minima f(x)=6sin(x)^2+6sin(x)
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 chain rule, which states that is where and .
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Step 1.2.2.1
To apply the Chain Rule, set as .
Step 1.2.2.2
Differentiate using the Power Rule which states that is where .
Step 1.2.2.3
Replace all occurrences of with .
Step 1.2.3
The derivative of with respect to is .
Step 1.2.4
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
The derivative of with respect to is .
Step 1.4
Reorder terms.
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 Product Rule which states that is where and .
Step 2.2.3
The derivative of with respect to is .
Step 2.2.4
The derivative of with respect to is .
Step 2.2.5
Raise to the power of .
Step 2.2.6
Raise to the power of .
Step 2.2.7
Use the power rule to combine exponents.
Step 2.2.8
Add and .
Step 2.2.9
Raise to the power of .
Step 2.2.10
Raise to the power of .
Step 2.2.11
Use the power rule to combine exponents.
Step 2.2.12
Add and .
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
The derivative of with respect to is .
Step 2.3.3
Multiply by .
Step 2.4
Simplify.
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Step 2.4.1
Apply the distributive property.
Step 2.4.2
Multiply by .
Step 3
To find the local maximum and minimum values of the function, set the derivative equal to and solve.
Step 4
Factor out of .
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Step 4.1
Factor out of .
Step 4.2
Factor out of .
Step 4.3
Factor out of .
Step 5
If any individual factor on the left side of the equation is equal to , the entire expression will be equal to .
Step 6
Set equal to and solve for .
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Step 6.1
Set equal to .
Step 6.2
Solve for .
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Step 6.2.1
Take the inverse cosine of both sides of the equation to extract from inside the cosine.
Step 6.2.2
Simplify the right side.
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Step 6.2.2.1
The exact value of is .
Step 6.2.3
The cosine function is positive in the first and fourth quadrants. To find the second solution, subtract the reference angle from to find the solution in the fourth quadrant.
Step 6.2.4
Simplify .
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Step 6.2.4.1
To write as a fraction with a common denominator, multiply by .
Step 6.2.4.2
Combine fractions.
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Step 6.2.4.2.1
Combine and .
Step 6.2.4.2.2
Combine the numerators over the common denominator.
Step 6.2.4.3
Simplify the numerator.
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Step 6.2.4.3.1
Multiply by .
Step 6.2.4.3.2
Subtract from .
Step 6.2.5
The solution to the equation .
Step 7
Set equal to and solve for .
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Step 7.1
Set equal to .
Step 7.2
Solve for .
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Step 7.2.1
Subtract from both sides of the equation.
Step 7.2.2
Divide each term in by and simplify.
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Step 7.2.2.1
Divide each term in by .
Step 7.2.2.2
Simplify the left side.
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Step 7.2.2.2.1
Cancel the common factor of .
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Step 7.2.2.2.1.1
Cancel the common factor.
Step 7.2.2.2.1.2
Divide by .
Step 7.2.2.3
Simplify the right side.
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Step 7.2.2.3.1
Move the negative in front of the fraction.
Step 7.2.3
Take the inverse sine of both sides of the equation to extract from inside the sine.
Step 7.2.4
Simplify the right side.
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Step 7.2.4.1
The exact value of is .
Step 7.2.5
The sine function is negative in the third and fourth quadrants. To find the second solution, subtract the solution from , to find a reference angle. Next, add this reference angle to to find the solution in the third quadrant.
Step 7.2.6
Simplify the expression to find the second solution.
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Step 7.2.6.1
Subtract from .
Step 7.2.6.2
The resulting angle of is positive, less than , and coterminal with .
Step 7.2.7
The solution to the equation .
Step 8
The final solution is all the values that make true.
Step 9
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 10
Evaluate the second derivative.
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Step 10.1
Simplify each term.
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Step 10.1.1
The exact value of is .
Step 10.1.2
Raising to any positive power yields .
Step 10.1.3
Multiply by .
Step 10.1.4
The exact value of is .
Step 10.1.5
One to any power is one.
Step 10.1.6
Multiply by .
Step 10.1.7
The exact value of is .
Step 10.1.8
Multiply by .
Step 10.2
Simplify by subtracting numbers.
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Step 10.2.1
Subtract from .
Step 10.2.2
Subtract from .
Step 11
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 12
Find the y-value when .
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Step 12.1
Replace the variable with in the expression.
Step 12.2
Simplify the result.
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Step 12.2.1
Simplify each term.
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Step 12.2.1.1
The exact value of is .
Step 12.2.1.2
One to any power is one.
Step 12.2.1.3
Multiply by .
Step 12.2.1.4
The exact value of is .
Step 12.2.1.5
Multiply by .
Step 12.2.2
Add and .
Step 12.2.3
The final answer is .
Step 13
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 14
Evaluate the second derivative.
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Step 14.1
Simplify each term.
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Step 14.1.1
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.
Step 14.1.2
The exact value of is .
Step 14.1.3
Raising to any positive power yields .
Step 14.1.4
Multiply by .
Step 14.1.5
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the fourth quadrant.
Step 14.1.6
The exact value of is .
Step 14.1.7
Multiply by .
Step 14.1.8
Raise to the power of .
Step 14.1.9
Multiply by .
Step 14.1.10
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the fourth quadrant.
Step 14.1.11
The exact value of is .
Step 14.1.12
Multiply .
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Step 14.1.12.1
Multiply by .
Step 14.1.12.2
Multiply by .
Step 14.2
Simplify by adding and subtracting.
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Step 14.2.1
Subtract from .
Step 14.2.2
Add and .
Step 15
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 16
Find the y-value when .
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Step 16.1
Replace the variable with in the expression.
Step 16.2
Simplify the result.
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Step 16.2.1
Simplify each term.
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Step 16.2.1.1
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the fourth quadrant.
Step 16.2.1.2
The exact value of is .
Step 16.2.1.3
Multiply by .
Step 16.2.1.4
Raise to the power of .
Step 16.2.1.5
Multiply by .
Step 16.2.1.6
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the fourth quadrant.
Step 16.2.1.7
The exact value of is .
Step 16.2.1.8
Multiply .
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Step 16.2.1.8.1
Multiply by .
Step 16.2.1.8.2
Multiply by .
Step 16.2.2
Subtract from .
Step 16.2.3
The final answer is .
Step 17
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 18
Evaluate the second derivative.
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Step 18.1
Simplify each term.
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Step 18.1.1
Add full rotations of until the angle is greater than or equal to and less than .
Step 18.1.2
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.
Step 18.1.3
The exact value of is .
Step 18.1.4
Apply the product rule to .
Step 18.1.5
Rewrite as .
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Step 18.1.5.1
Use to rewrite as .
Step 18.1.5.2
Apply the power rule and multiply exponents, .
Step 18.1.5.3
Combine and .
Step 18.1.5.4
Cancel the common factor of .
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Step 18.1.5.4.1
Cancel the common factor.
Step 18.1.5.4.2
Rewrite the expression.
Step 18.1.5.5
Evaluate the exponent.
Step 18.1.6
Raise to the power of .
Step 18.1.7
Cancel the common factor of .
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Step 18.1.7.1
Factor out of .
Step 18.1.7.2
Cancel the common factor.
Step 18.1.7.3
Rewrite the expression.
Step 18.1.8
Multiply by .
Step 18.1.9
Add full rotations of until the angle is greater than or equal to and less than .
Step 18.1.10
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the fourth quadrant.
Step 18.1.11
The exact value of is .
Step 18.1.12
Use the power rule to distribute the exponent.
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Step 18.1.12.1
Apply the product rule to .
Step 18.1.12.2
Apply the product rule to .
Step 18.1.13
Raise to the power of .
Step 18.1.14
Multiply by .
Step 18.1.15
One to any power is one.
Step 18.1.16
Raise to the power of .
Step 18.1.17
Cancel the common factor of .
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Step 18.1.17.1
Factor out of .
Step 18.1.17.2
Cancel the common factor.
Step 18.1.17.3
Rewrite the expression.
Step 18.1.18
Add full rotations of until the angle is greater than or equal to and less than .
Step 18.1.19
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the fourth quadrant.
Step 18.1.20
The exact value of is .
Step 18.1.21
Cancel the common factor of .
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Step 18.1.21.1
Move the leading negative in into the numerator.
Step 18.1.21.2
Factor out of .
Step 18.1.21.3
Cancel the common factor.
Step 18.1.21.4
Rewrite the expression.
Step 18.1.22
Multiply by .
Step 18.2
Simplify by adding and subtracting.
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Step 18.2.1
Subtract from .
Step 18.2.2
Add and .
Step 19
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 20
Find the y-value when .
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Step 20.1
Replace the variable with in the expression.
Step 20.2
Simplify the result.
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Step 20.2.1
Simplify each term.
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Step 20.2.1.1
Add full rotations of until the angle is greater than or equal to and less than .
Step 20.2.1.2
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the fourth quadrant.
Step 20.2.1.3
The exact value of is .
Step 20.2.1.4
Use the power rule to distribute the exponent.
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Step 20.2.1.4.1
Apply the product rule to .
Step 20.2.1.4.2
Apply the product rule to .
Step 20.2.1.5
Raise to the power of .
Step 20.2.1.6
Multiply by .
Step 20.2.1.7
One to any power is one.
Step 20.2.1.8
Raise to the power of .
Step 20.2.1.9
Cancel the common factor of .
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Step 20.2.1.9.1
Factor out of .
Step 20.2.1.9.2
Factor out of .
Step 20.2.1.9.3
Cancel the common factor.
Step 20.2.1.9.4
Rewrite the expression.
Step 20.2.1.10
Combine and .
Step 20.2.1.11
Add full rotations of until the angle is greater than or equal to and less than .
Step 20.2.1.12
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the fourth quadrant.
Step 20.2.1.13
The exact value of is .
Step 20.2.1.14
Cancel the common factor of .
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Step 20.2.1.14.1
Move the leading negative in into the numerator.
Step 20.2.1.14.2
Factor out of .
Step 20.2.1.14.3
Cancel the common factor.
Step 20.2.1.14.4
Rewrite the expression.
Step 20.2.1.15
Multiply by .
Step 20.2.2
To write as a fraction with a common denominator, multiply by .
Step 20.2.3
Combine and .
Step 20.2.4
Combine the numerators over the common denominator.
Step 20.2.5
Simplify the numerator.
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Step 20.2.5.1
Multiply by .
Step 20.2.5.2
Subtract from .
Step 20.2.6
Move the negative in front of the fraction.
Step 20.2.7
The final answer is .
Step 21
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 22
Evaluate the second derivative.
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Step 22.1
Simplify each term.
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Step 22.1.1
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the third quadrant.
Step 22.1.2
The exact value of is .
Step 22.1.3
Use the power rule to distribute the exponent.
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Step 22.1.3.1
Apply the product rule to .
Step 22.1.3.2
Apply the product rule to .
Step 22.1.4
Raise to the power of .
Step 22.1.5
Multiply by .
Step 22.1.6
Rewrite as .
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Step 22.1.6.1
Use to rewrite as .
Step 22.1.6.2
Apply the power rule and multiply exponents, .
Step 22.1.6.3
Combine and .
Step 22.1.6.4
Cancel the common factor of .
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Step 22.1.6.4.1
Cancel the common factor.
Step 22.1.6.4.2
Rewrite the expression.
Step 22.1.6.5
Evaluate the exponent.
Step 22.1.7
Raise to the power of .
Step 22.1.8
Cancel the common factor of .
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Step 22.1.8.1
Factor out of .
Step 22.1.8.2
Cancel the common factor.
Step 22.1.8.3
Rewrite the expression.
Step 22.1.9
Multiply by .
Step 22.1.10
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the third quadrant.
Step 22.1.11
The exact value of is .
Step 22.1.12
Use the power rule to distribute the exponent.
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Step 22.1.12.1
Apply the product rule to .
Step 22.1.12.2
Apply the product rule to .
Step 22.1.13
Raise to the power of .
Step 22.1.14
Multiply by .
Step 22.1.15
One to any power is one.
Step 22.1.16
Raise to the power of .
Step 22.1.17
Cancel the common factor of .
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Step 22.1.17.1
Factor out of .
Step 22.1.17.2
Cancel the common factor.
Step 22.1.17.3
Rewrite the expression.
Step 22.1.18
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the third quadrant.
Step 22.1.19
The exact value of is .
Step 22.1.20
Cancel the common factor of .
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Step 22.1.20.1
Move the leading negative in into the numerator.
Step 22.1.20.2
Factor out of .
Step 22.1.20.3
Cancel the common factor.
Step 22.1.20.4
Rewrite the expression.
Step 22.1.21
Multiply by .
Step 22.2
Simplify by adding and subtracting.
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Step 22.2.1
Subtract from .
Step 22.2.2
Add and .
Step 23
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 24
Find the y-value when .
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Step 24.1
Replace the variable with in the expression.
Step 24.2
Simplify the result.
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Step 24.2.1
Simplify each term.
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Step 24.2.1.1
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the third quadrant.
Step 24.2.1.2
The exact value of is .
Step 24.2.1.3
Use the power rule to distribute the exponent.
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Step 24.2.1.3.1
Apply the product rule to .
Step 24.2.1.3.2
Apply the product rule to .
Step 24.2.1.4
Raise to the power of .
Step 24.2.1.5
Multiply by .
Step 24.2.1.6
One to any power is one.
Step 24.2.1.7
Raise to the power of .
Step 24.2.1.8
Cancel the common factor of .
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Step 24.2.1.8.1
Factor out of .
Step 24.2.1.8.2
Factor out of .
Step 24.2.1.8.3
Cancel the common factor.
Step 24.2.1.8.4
Rewrite the expression.
Step 24.2.1.9
Combine and .
Step 24.2.1.10
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the third quadrant.
Step 24.2.1.11
The exact value of is .
Step 24.2.1.12
Cancel the common factor of .
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Step 24.2.1.12.1
Move the leading negative in into the numerator.
Step 24.2.1.12.2
Factor out of .
Step 24.2.1.12.3
Cancel the common factor.
Step 24.2.1.12.4
Rewrite the expression.
Step 24.2.1.13
Multiply by .
Step 24.2.2
To write as a fraction with a common denominator, multiply by .
Step 24.2.3
Combine and .
Step 24.2.4
Combine the numerators over the common denominator.
Step 24.2.5
Simplify the numerator.
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Step 24.2.5.1
Multiply by .
Step 24.2.5.2
Subtract from .
Step 24.2.6
Move the negative in front of the fraction.
Step 24.2.7
The final answer is .
Step 25
These are the local extrema for .
is a local maxima
is a local maxima
is a local minima
is a local minima
Step 26