Calculus Examples

Find Where Increasing/Decreasing Using Derivatives f(x)=100x(2x+3)(x-5)
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
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.2
Differentiate using the Product Rule which states that is where and .
Step 1.1.3
Differentiate.
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Step 1.1.3.1
By the Sum Rule, 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
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.3.4
Simplify the expression.
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Step 1.1.3.4.1
Add and .
Step 1.1.3.4.2
Multiply by .
Step 1.1.4
Differentiate using the Product Rule which states that is where and .
Step 1.1.5
Differentiate.
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Step 1.1.5.1
By the Sum Rule, the derivative of with respect to is .
Step 1.1.5.2
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.5.3
Differentiate using the Power Rule which states that is where .
Step 1.1.5.4
Multiply by .
Step 1.1.5.5
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.5.6
Simplify the expression.
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Step 1.1.5.6.1
Add and .
Step 1.1.5.6.2
Move to the left of .
Step 1.1.5.7
Differentiate using the Power Rule which states that is where .
Step 1.1.5.8
Simplify by adding terms.
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Step 1.1.5.8.1
Multiply by .
Step 1.1.5.8.2
Add and .
Step 1.1.6
Simplify.
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Step 1.1.6.1
Apply the distributive property.
Step 1.1.6.2
Apply the distributive property.
Step 1.1.6.3
Apply the distributive property.
Step 1.1.6.4
Apply the distributive property.
Step 1.1.6.5
Apply the distributive property.
Step 1.1.6.6
Apply the distributive property.
Step 1.1.6.7
Combine terms.
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Step 1.1.6.7.1
Raise to the power of .
Step 1.1.6.7.2
Raise to the power of .
Step 1.1.6.7.3
Use the power rule to combine exponents.
Step 1.1.6.7.4
Add and .
Step 1.1.6.7.5
Multiply by .
Step 1.1.6.7.6
Move to the left of .
Step 1.1.6.7.7
Multiply by .
Step 1.1.6.7.8
Raise to the power of .
Step 1.1.6.7.9
Raise to the power of .
Step 1.1.6.7.10
Use the power rule to combine exponents.
Step 1.1.6.7.11
Add and .
Step 1.1.6.7.12
Multiply by .
Step 1.1.6.7.13
Multiply by .
Step 1.1.6.7.14
Multiply by .
Step 1.1.6.7.15
Move to the left of .
Step 1.1.6.7.16
Multiply by .
Step 1.1.6.7.17
Multiply by .
Step 1.1.6.7.18
Multiply by .
Step 1.1.6.7.19
Add and .
Step 1.1.6.7.20
Add and .
Step 1.1.6.7.21
Subtract from .
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
Factor out of .
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Step 2.2.1
Factor out of .
Step 2.2.2
Factor out of .
Step 2.2.3
Factor out of .
Step 2.2.4
Factor out of .
Step 2.2.5
Factor out of .
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
Divide by .
Step 2.4
Use the quadratic formula to find the solutions.
Step 2.5
Substitute the values , , and into the quadratic formula and solve for .
Step 2.6
Simplify.
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Step 2.6.1
Simplify the numerator.
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Step 2.6.1.1
Raise to the power of .
Step 2.6.1.2
Multiply .
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Step 2.6.1.2.1
Multiply by .
Step 2.6.1.2.2
Multiply by .
Step 2.6.1.3
Add and .
Step 2.6.1.4
Rewrite as .
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Step 2.6.1.4.1
Factor out of .
Step 2.6.1.4.2
Rewrite as .
Step 2.6.1.5
Pull terms out from under the radical.
Step 2.6.2
Multiply by .
Step 2.6.3
Simplify .
Step 2.7
Simplify the expression to solve for the portion of the .
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Step 2.7.1
Simplify the numerator.
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Step 2.7.1.1
Raise to the power of .
Step 2.7.1.2
Multiply .
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Step 2.7.1.2.1
Multiply by .
Step 2.7.1.2.2
Multiply by .
Step 2.7.1.3
Add and .
Step 2.7.1.4
Rewrite as .
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Step 2.7.1.4.1
Factor out of .
Step 2.7.1.4.2
Rewrite as .
Step 2.7.1.5
Pull terms out from under the radical.
Step 2.7.2
Multiply by .
Step 2.7.3
Simplify .
Step 2.7.4
Change the to .
Step 2.8
Simplify the expression to solve for the portion of the .
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Step 2.8.1
Simplify the numerator.
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Step 2.8.1.1
Raise to the power of .
Step 2.8.1.2
Multiply .
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Step 2.8.1.2.1
Multiply by .
Step 2.8.1.2.2
Multiply by .
Step 2.8.1.3
Add and .
Step 2.8.1.4
Rewrite as .
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Step 2.8.1.4.1
Factor out of .
Step 2.8.1.4.2
Rewrite as .
Step 2.8.1.5
Pull terms out from under the radical.
Step 2.8.2
Multiply by .
Step 2.8.3
Simplify .
Step 2.8.4
Change the to .
Step 2.9
The final answer is the combination of both solutions.
Step 3
The values which make the derivative equal to are .
Step 4
Split into separate intervals around the values that make the derivative or undefined.
Step 5
Substitute a value from the interval into the derivative to determine if the function is increasing or decreasing.
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Step 5.1
Replace the variable with in the expression.
Step 5.2
Simplify the result.
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Step 5.2.1
Simplify each term.
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Step 5.2.1.1
Raise to the power of .
Step 5.2.1.2
Multiply by .
Step 5.2.1.3
Multiply by .
Step 5.2.2
Simplify by adding and subtracting.
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Step 5.2.2.1
Add and .
Step 5.2.2.2
Subtract from .
Step 5.2.3
The final answer is .
Step 5.3
At the derivative is . Since this is positive, the function is increasing on .
Increasing on since
Increasing on since
Step 6
Substitute a value from the interval into the derivative to determine if the function is increasing or decreasing.
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Step 6.1
Replace the variable with in the expression.
Step 6.2
Simplify the result.
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Step 6.2.1
Simplify each term.
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Step 6.2.1.1
Raise to the power of .
Step 6.2.1.2
Multiply by .
Step 6.2.1.3
Multiply by .
Step 6.2.2
Simplify by subtracting numbers.
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Step 6.2.2.1
Subtract from .
Step 6.2.2.2
Subtract from .
Step 6.2.3
The final answer is .
Step 6.3
At the derivative is . Since this is negative, the function is decreasing on .
Decreasing on since
Decreasing on since
Step 7
Substitute a value from the interval into the derivative to determine if the function is increasing or decreasing.
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Step 7.1
Replace the variable with in the expression.
Step 7.2
Simplify the result.
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Step 7.2.1
Simplify each term.
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Step 7.2.1.1
Raise to the power of .
Step 7.2.1.2
Multiply by .
Step 7.2.1.3
Multiply by .
Step 7.2.2
Simplify by subtracting numbers.
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Step 7.2.2.1
Subtract from .
Step 7.2.2.2
Subtract from .
Step 7.2.3
The final answer is .
Step 7.3
At the derivative is . Since this is positive, the function is increasing on .
Increasing on since
Increasing on since
Step 8
List the intervals on which the function is increasing and decreasing.
Increasing on:
Decreasing on:
Step 9