Calculus Examples

Find the Critical Points 2cos(4x)+4x
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
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.2.2
Differentiate using the chain rule, which states that is where and .
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Step 1.1.2.2.1
To apply the Chain Rule, set as .
Step 1.1.2.2.2
The derivative of with respect to is .
Step 1.1.2.2.3
Replace all occurrences of with .
Step 1.1.2.3
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.2.4
Differentiate using the Power Rule which states that is where .
Step 1.1.2.5
Multiply by .
Step 1.1.2.6
Multiply by .
Step 1.1.2.7
Multiply by .
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
Reorder terms.
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
Subtract from both sides of the equation.
Step 2.3
Divide each term in by and simplify.
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Step 2.3.1
Divide each term in by .
Step 2.3.2
Simplify the left side.
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Step 2.3.2.1
Cancel the common factor of .
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Step 2.3.2.1.1
Cancel the common factor.
Step 2.3.2.1.2
Divide by .
Step 2.3.3
Simplify the right side.
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Step 2.3.3.1
Cancel the common factor of and .
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Step 2.3.3.1.1
Factor out of .
Step 2.3.3.1.2
Cancel the common factors.
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Step 2.3.3.1.2.1
Factor out of .
Step 2.3.3.1.2.2
Cancel the common factor.
Step 2.3.3.1.2.3
Rewrite the expression.
Step 2.4
Take the inverse sine of both sides of the equation to extract from inside the sine.
Step 2.5
Simplify the right side.
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Step 2.5.1
The exact value of is .
Step 2.6
Divide each term in by and simplify.
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Step 2.6.1
Divide each term in by .
Step 2.6.2
Simplify the left side.
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Step 2.6.2.1
Cancel the common factor of .
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Step 2.6.2.1.1
Cancel the common factor.
Step 2.6.2.1.2
Divide by .
Step 2.6.3
Simplify the right side.
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Step 2.6.3.1
Multiply the numerator by the reciprocal of the denominator.
Step 2.6.3.2
Multiply .
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Step 2.6.3.2.1
Multiply by .
Step 2.6.3.2.2
Multiply by .
Step 2.7
The sine function is positive in the first and second quadrants. To find the second solution, subtract the reference angle from to find the solution in the second quadrant.
Step 2.8
Solve for .
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Step 2.8.1
Simplify.
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Step 2.8.1.1
To write as a fraction with a common denominator, multiply by .
Step 2.8.1.2
Combine and .
Step 2.8.1.3
Combine the numerators over the common denominator.
Step 2.8.1.4
Subtract from .
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Step 2.8.1.4.1
Reorder and .
Step 2.8.1.4.2
Subtract from .
Step 2.8.2
Divide each term in by and simplify.
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Step 2.8.2.1
Divide each term in by .
Step 2.8.2.2
Simplify the left side.
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Step 2.8.2.2.1
Cancel the common factor of .
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Step 2.8.2.2.1.1
Cancel the common factor.
Step 2.8.2.2.1.2
Divide by .
Step 2.8.2.3
Simplify the right side.
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Step 2.8.2.3.1
Multiply the numerator by the reciprocal of the denominator.
Step 2.8.2.3.2
Multiply .
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Step 2.8.2.3.2.1
Multiply by .
Step 2.8.2.3.2.2
Multiply by .
Step 2.9
Find the period of .
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Step 2.9.1
The period of the function can be calculated using .
Step 2.9.2
Replace with in the formula for period.
Step 2.9.3
The absolute value is the distance between a number and zero. The distance between and is .
Step 2.9.4
Cancel the common factor of and .
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Step 2.9.4.1
Factor out of .
Step 2.9.4.2
Cancel the common factors.
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Step 2.9.4.2.1
Factor out of .
Step 2.9.4.2.2
Cancel the common factor.
Step 2.9.4.2.3
Rewrite the expression.
Step 2.10
The period of the function is so values will repeat every radians in both directions.
, 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
Simplify each term.
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Step 4.1.2.1
Cancel the common factor of .
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Step 4.1.2.1.1
Factor out of .
Step 4.1.2.1.2
Cancel the common factor.
Step 4.1.2.1.3
Rewrite the expression.
Step 4.1.2.2
The exact value of is .
Step 4.1.2.3
Cancel the common factor of .
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Step 4.1.2.3.1
Cancel the common factor.
Step 4.1.2.3.2
Rewrite the expression.
Step 4.1.2.4
Cancel the common factor of .
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Step 4.1.2.4.1
Factor out of .
Step 4.1.2.4.2
Cancel the common factor.
Step 4.1.2.4.3
Rewrite the expression.
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
Cancel the common factor of .
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Step 4.2.2.1.1
Factor out of .
Step 4.2.2.1.2
Cancel the common factor.
Step 4.2.2.1.3
Rewrite the expression.
Step 4.2.2.2
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.2.2.3
The exact value of is .
Step 4.2.2.4
Cancel the common factor of .
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Step 4.2.2.4.1
Cancel the common factor.
Step 4.2.2.4.2
Rewrite the expression.
Step 4.2.2.5
Cancel the common factor of .
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Step 4.2.2.5.1
Factor out of .
Step 4.2.2.5.2
Cancel the common factor.
Step 4.2.2.5.3
Rewrite the expression.
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
Cancel the common factor of .
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Step 4.3.2.1.1
Factor out of .
Step 4.3.2.1.2
Cancel the common factor.
Step 4.3.2.1.3
Rewrite the expression.
Step 4.3.2.2
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.3.2.3
The exact value of is .
Step 4.3.2.4
Cancel the common factor of .
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Step 4.3.2.4.1
Cancel the common factor.
Step 4.3.2.4.2
Rewrite the expression.
Step 4.3.2.5
Cancel the common factor of .
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Step 4.3.2.5.1
Factor out of .
Step 4.3.2.5.2
Cancel the common factor.
Step 4.3.2.5.3
Rewrite the expression.
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
Cancel the common factor of .
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Step 4.4.2.1.1
Factor out of .
Step 4.4.2.1.2
Cancel the common factor.
Step 4.4.2.1.3
Rewrite the expression.
Step 4.4.2.2
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.4.2.3
The exact value of is .
Step 4.4.2.4
Cancel the common factor of .
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Step 4.4.2.4.1
Cancel the common factor.
Step 4.4.2.4.2
Rewrite the expression.
Step 4.4.2.5
Cancel the common factor of .
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Step 4.4.2.5.1
Factor out of .
Step 4.4.2.5.2
Cancel the common factor.
Step 4.4.2.5.3
Rewrite the expression.
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
Cancel the common factor of .
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Step 4.5.2.1.1
Factor out of .
Step 4.5.2.1.2
Cancel the common factor.
Step 4.5.2.1.3
Rewrite the expression.
Step 4.5.2.2
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.5.2.3
The exact value of is .
Step 4.5.2.4
Cancel the common factor of .
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Step 4.5.2.4.1
Cancel the common factor.
Step 4.5.2.4.2
Rewrite the expression.
Step 4.5.2.5
Cancel the common factor of .
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Step 4.5.2.5.1
Factor out of .
Step 4.5.2.5.2
Cancel the common factor.
Step 4.5.2.5.3
Rewrite the expression.
Step 4.6
Evaluate at .
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Step 4.6.1
Substitute for .
Step 4.6.2
Simplify each term.
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Step 4.6.2.1
Cancel the common factor of .
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Step 4.6.2.1.1
Factor out of .
Step 4.6.2.1.2
Cancel the common factor.
Step 4.6.2.1.3
Rewrite the expression.
Step 4.6.2.2
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 second quadrant.
Step 4.6.2.3
The exact value of is .
Step 4.6.2.4
Cancel the common factor of .
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Step 4.6.2.4.1
Move the leading negative in into the numerator.
Step 4.6.2.4.2
Cancel the common factor.
Step 4.6.2.4.3
Rewrite the expression.
Step 4.6.2.5
Cancel the common factor of .
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Step 4.6.2.5.1
Factor out of .
Step 4.6.2.5.2
Cancel the common factor.
Step 4.6.2.5.3
Rewrite the expression.
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
Cancel the common factor of .
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Step 4.7.2.1.1
Factor out of .
Step 4.7.2.1.2
Cancel the common factor.
Step 4.7.2.1.3
Rewrite the expression.
Step 4.7.2.2
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.7.2.3
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 second quadrant.
Step 4.7.2.4
The exact value of is .
Step 4.7.2.5
Cancel the common factor of .
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Step 4.7.2.5.1
Move the leading negative in into the numerator.
Step 4.7.2.5.2
Cancel the common factor.
Step 4.7.2.5.3
Rewrite the expression.
Step 4.7.2.6
Cancel the common factor of .
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Step 4.7.2.6.1
Factor out of .
Step 4.7.2.6.2
Cancel the common factor.
Step 4.7.2.6.3
Rewrite the expression.
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
Cancel the common factor of .
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Step 4.8.2.1.1
Factor out of .
Step 4.8.2.1.2
Cancel the common factor.
Step 4.8.2.1.3
Rewrite the expression.
Step 4.8.2.2
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.8.2.3
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 second quadrant.
Step 4.8.2.4
The exact value of is .
Step 4.8.2.5
Cancel the common factor of .
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Step 4.8.2.5.1
Move the leading negative in into the numerator.
Step 4.8.2.5.2
Cancel the common factor.
Step 4.8.2.5.3
Rewrite the expression.
Step 4.8.2.6
Cancel the common factor of .
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Step 4.8.2.6.1
Factor out of .
Step 4.8.2.6.2
Cancel the common factor.
Step 4.8.2.6.3
Rewrite the expression.
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
Cancel the common factor of .
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Step 4.9.2.1.1
Factor out of .
Step 4.9.2.1.2
Cancel the common factor.
Step 4.9.2.1.3
Rewrite the expression.
Step 4.9.2.2
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.9.2.3
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 second quadrant.
Step 4.9.2.4
The exact value of is .
Step 4.9.2.5
Cancel the common factor of .
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Step 4.9.2.5.1
Move the leading negative in into the numerator.
Step 4.9.2.5.2
Cancel the common factor.
Step 4.9.2.5.3
Rewrite the expression.
Step 4.9.2.6
Cancel the common factor of .
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Step 4.9.2.6.1
Factor out of .
Step 4.9.2.6.2
Cancel the common factor.
Step 4.9.2.6.3
Rewrite the expression.
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
Cancel the common factor of .
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Step 4.10.2.1.1
Factor out of .
Step 4.10.2.1.2
Cancel the common factor.
Step 4.10.2.1.3
Rewrite the expression.
Step 4.10.2.2
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.10.2.3
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 second quadrant.
Step 4.10.2.4
The exact value of is .
Step 4.10.2.5
Cancel the common factor of .
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Step 4.10.2.5.1
Move the leading negative in into the numerator.
Step 4.10.2.5.2
Cancel the common factor.
Step 4.10.2.5.3
Rewrite the expression.
Step 4.10.2.6
Cancel the common factor of .
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Step 4.10.2.6.1
Factor out of .
Step 4.10.2.6.2
Cancel the common factor.
Step 4.10.2.6.3
Rewrite the expression.
Step 4.11
List all of the points.
Step 5