Calculus Examples

Find the Critical Points h(x)=sin(2x)+cos(x)
Step 1
Find the first 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
Differentiate using the chain rule, which states that is where and .
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Step 1.1.2.1.1
To apply the Chain Rule, set as .
Step 1.1.2.1.2
The derivative of with respect to is .
Step 1.1.2.1.3
Replace all occurrences of with .
Step 1.1.2.2
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.2.3
Differentiate using the Power Rule which states that is where .
Step 1.1.2.4
Multiply by .
Step 1.1.2.5
Move to the left of .
Step 1.1.3
The derivative of with respect to is .
Step 1.2
The first derivative of with respect to is .
Step 2
Set the first derivative equal to then solve the equation .
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Step 2.1
Set the first derivative equal to .
Step 2.2
Use the double-angle identity to transform to .
Step 2.3
Simplify the left side.
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Step 2.3.1
Simplify each term.
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Step 2.3.1.1
Apply the distributive property.
Step 2.3.1.2
Multiply by .
Step 2.3.1.3
Multiply by .
Step 2.4
Solve the equation for .
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Step 2.4.1
Substitute for .
Step 2.4.2
Use the quadratic formula to find the solutions.
Step 2.4.3
Substitute the values , , and into the quadratic formula and solve for .
Step 2.4.4
Simplify.
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Step 2.4.4.1
Simplify the numerator.
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Step 2.4.4.1.1
Raise to the power of .
Step 2.4.4.1.2
Multiply .
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Step 2.4.4.1.2.1
Multiply by .
Step 2.4.4.1.2.2
Multiply by .
Step 2.4.4.1.3
Add and .
Step 2.4.4.2
Multiply by .
Step 2.4.4.3
Move the negative in front of the fraction.
Step 2.4.5
Simplify the expression to solve for the portion of the .
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Step 2.4.5.1
Simplify the numerator.
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Step 2.4.5.1.1
Raise to the power of .
Step 2.4.5.1.2
Multiply .
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Step 2.4.5.1.2.1
Multiply by .
Step 2.4.5.1.2.2
Multiply by .
Step 2.4.5.1.3
Add and .
Step 2.4.5.2
Multiply by .
Step 2.4.5.3
Move the negative in front of the fraction.
Step 2.4.5.4
Change the to .
Step 2.4.6
Simplify the expression to solve for the portion of the .
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Step 2.4.6.1
Simplify the numerator.
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Step 2.4.6.1.1
Raise to the power of .
Step 2.4.6.1.2
Multiply .
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Step 2.4.6.1.2.1
Multiply by .
Step 2.4.6.1.2.2
Multiply by .
Step 2.4.6.1.3
Add and .
Step 2.4.6.2
Multiply by .
Step 2.4.6.3
Move the negative in front of the fraction.
Step 2.4.6.4
Change the to .
Step 2.4.7
The final answer is the combination of both solutions.
Step 2.4.8
Substitute for .
Step 2.4.9
Set up each of the solutions to solve for .
Step 2.4.10
Solve for in .
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Step 2.4.10.1
Take the inverse sine of both sides of the equation to extract from inside the sine.
Step 2.4.10.2
Simplify the right side.
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Step 2.4.10.2.1
Evaluate .
Step 2.4.10.3
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 2.4.10.4
Simplify the expression to find the second solution.
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Step 2.4.10.4.1
Subtract from .
Step 2.4.10.4.2
The resulting angle of is positive, less than , and coterminal with .
Step 2.4.10.5
Find the period of .
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Step 2.4.10.5.1
The period of the function can be calculated using .
Step 2.4.10.5.2
Replace with in the formula for period.
Step 2.4.10.5.3
The absolute value is the distance between a number and zero. The distance between and is .
Step 2.4.10.5.4
Divide by .
Step 2.4.10.6
Add to every negative angle to get positive angles.
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Step 2.4.10.6.1
Add to to find the positive angle.
Step 2.4.10.6.2
Subtract from .
Step 2.4.10.6.3
List the new angles.
Step 2.4.10.7
The period of the function is so values will repeat every radians in both directions.
, for any integer
, for any integer
Step 2.4.11
Solve for in .
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Step 2.4.11.1
Take the inverse sine of both sides of the equation to extract from inside the sine.
Step 2.4.11.2
Simplify the right side.
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Step 2.4.11.2.1
Evaluate .
Step 2.4.11.3
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 2.4.11.4
Simplify the expression to find the second solution.
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Step 2.4.11.4.1
Subtract from .
Step 2.4.11.4.2
The resulting angle of is positive, less than , and coterminal with .
Step 2.4.11.5
Find the period of .
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Step 2.4.11.5.1
The period of the function can be calculated using .
Step 2.4.11.5.2
Replace with in the formula for period.
Step 2.4.11.5.3
The absolute value is the distance between a number and zero. The distance between and is .
Step 2.4.11.5.4
Divide by .
Step 2.4.11.6
The period of the function is so values will repeat every radians in both directions.
, for any integer
, for any integer
Step 2.4.12
List all of the solutions.
, for any integer
, for any integer
, for any integer
Step 3
Find the values where the derivative is undefined.
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Step 3.1
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 4
Evaluate at each value where the derivative is or undefined.
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Step 4.1
Evaluate at .
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Step 4.1.1
Substitute for .
Step 4.1.2
Multiply by .
Step 4.2
Evaluate at .
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Step 4.2.1
Substitute for .
Step 4.2.2
Simplify each term.
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Step 4.2.2.1
Add and .
Step 4.2.2.2
Multiply by .
Step 4.2.2.3
Add and .
Step 4.3
Evaluate at .
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Step 4.3.1
Substitute for .
Step 4.3.2
Simplify each term.
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Step 4.3.2.1
Add and .
Step 4.3.2.2
Multiply by .
Step 4.3.2.3
Add and .
Step 4.4
Evaluate at .
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Step 4.4.1
Substitute for .
Step 4.4.2
Simplify each term.
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Step 4.4.2.1
Add and .
Step 4.4.2.2
Multiply by .
Step 4.4.2.3
Add and .
Step 4.5
Evaluate at .
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Step 4.5.1
Substitute for .
Step 4.5.2
Simplify each term.
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Step 4.5.2.1
Add and .
Step 4.5.2.2
Multiply by .
Step 4.5.2.3
Add and .
Step 4.6
Evaluate at .
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Step 4.6.1
Substitute for .
Step 4.6.2
Multiply by .
Step 4.7
Evaluate at .
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Step 4.7.1
Substitute for .
Step 4.7.2
Simplify each term.
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Step 4.7.2.1
Add and .
Step 4.7.2.2
Multiply by .
Step 4.7.2.3
Add and .
Step 4.8
Evaluate at .
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Step 4.8.1
Substitute for .
Step 4.8.2
Simplify each term.
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Step 4.8.2.1
Add and .
Step 4.8.2.2
Multiply by .
Step 4.8.2.3
Add and .
Step 4.9
Evaluate at .
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Step 4.9.1
Substitute for .
Step 4.9.2
Simplify each term.
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Step 4.9.2.1
Add and .
Step 4.9.2.2
Multiply by .
Step 4.9.2.3
Add and .
Step 4.10
Evaluate at .
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Step 4.10.1
Substitute for .
Step 4.10.2
Simplify each term.
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Step 4.10.2.1
Add and .
Step 4.10.2.2
Multiply by .
Step 4.10.2.3
Add and .
Step 4.11
Evaluate at .
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Step 4.11.1
Substitute for .
Step 4.11.2
Multiply by .
Step 4.12
Evaluate at .
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Step 4.12.1
Substitute for .
Step 4.12.2
Simplify each term.
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Step 4.12.2.1
Add and .
Step 4.12.2.2
Multiply by .
Step 4.12.2.3
Add and .
Step 4.13
Evaluate at .
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Step 4.13.1
Substitute for .
Step 4.13.2
Simplify each term.
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Step 4.13.2.1
Add and .
Step 4.13.2.2
Multiply by .
Step 4.13.2.3
Add and .
Step 4.14
Evaluate at .
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Step 4.14.1
Substitute for .
Step 4.14.2
Simplify each term.
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Step 4.14.2.1
Add and .
Step 4.14.2.2
Multiply by .
Step 4.14.2.3
Add and .
Step 4.15
Evaluate at .
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Step 4.15.1
Substitute for .
Step 4.15.2
Simplify each term.
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Step 4.15.2.1
Add and .
Step 4.15.2.2
Multiply by .
Step 4.15.2.3
Add and .
Step 4.16
Evaluate at .
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Step 4.16.1
Substitute for .
Step 4.16.2
Multiply by .
Step 4.17
Evaluate at .
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Step 4.17.1
Substitute for .
Step 4.17.2
Simplify each term.
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Step 4.17.2.1
Add and .
Step 4.17.2.2
Multiply by .
Step 4.17.2.3
Add and .
Step 4.18
Evaluate at .
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Step 4.18.1
Substitute for .
Step 4.18.2
Simplify each term.
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Step 4.18.2.1
Add and .
Step 4.18.2.2
Multiply by .
Step 4.18.2.3
Add and .
Step 4.19
Evaluate at .
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Step 4.19.1
Substitute for .
Step 4.19.2
Simplify each term.
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Step 4.19.2.1
Add and .
Step 4.19.2.2
Multiply by .
Step 4.19.2.3
Add and .
Step 4.20
Evaluate at .
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Step 4.20.1
Substitute for .
Step 4.20.2
Simplify each term.
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Step 4.20.2.1
Add and .
Step 4.20.2.2
Multiply by .
Step 4.20.2.3
Add and .
Step 4.21
List all of the points.
, for any integer
, for any integer
Step 5