Calculus Examples

Find Where Increasing/Decreasing Using Derivatives f(x)=4(x+2) square root of 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
Differentiate using the Constant Multiple Rule.
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Step 1.1.1.1
Use to rewrite as .
Step 1.1.1.2
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 using the Power Rule which states that is where .
Step 1.1.4
To write as a fraction with a common denominator, multiply by .
Step 1.1.5
Combine and .
Step 1.1.6
Combine the numerators over the common denominator.
Step 1.1.7
Simplify the numerator.
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Step 1.1.7.1
Multiply by .
Step 1.1.7.2
Subtract from .
Step 1.1.8
Combine fractions.
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Step 1.1.8.1
Move the negative in front of the fraction.
Step 1.1.8.2
Combine and .
Step 1.1.8.3
Move to the denominator using the negative exponent rule .
Step 1.1.9
By the Sum Rule, the derivative of with respect to is .
Step 1.1.10
Differentiate using the Power Rule which states that is where .
Step 1.1.11
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.12
Simplify the expression.
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Step 1.1.12.1
Add and .
Step 1.1.12.2
Multiply by .
Step 1.1.13
Simplify.
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Step 1.1.13.1
Apply the distributive property.
Step 1.1.13.2
Apply the distributive property.
Step 1.1.13.3
Combine terms.
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Step 1.1.13.3.1
Combine and .
Step 1.1.13.3.2
Move to the numerator using the negative exponent rule .
Step 1.1.13.3.3
Multiply by by adding the exponents.
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Step 1.1.13.3.3.1
Multiply by .
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Step 1.1.13.3.3.1.1
Raise to the power of .
Step 1.1.13.3.3.1.2
Use the power rule to combine exponents.
Step 1.1.13.3.3.2
Write as a fraction with a common denominator.
Step 1.1.13.3.3.3
Combine the numerators over the common denominator.
Step 1.1.13.3.3.4
Subtract from .
Step 1.1.13.3.4
Combine and .
Step 1.1.13.3.5
Factor out of .
Step 1.1.13.3.6
Cancel the common factors.
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Step 1.1.13.3.6.1
Factor out of .
Step 1.1.13.3.6.2
Cancel the common factor.
Step 1.1.13.3.6.3
Rewrite the expression.
Step 1.1.13.3.6.4
Divide by .
Step 1.1.13.3.7
Combine and .
Step 1.1.13.3.8
Cancel the common factor.
Step 1.1.13.3.9
Rewrite the expression.
Step 1.1.13.3.10
Combine and .
Step 1.1.13.3.11
Add and .
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
Find the LCD of the terms in the equation.
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Step 2.2.1
Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.
Step 2.2.2
The LCM of one and any expression is the expression.
Step 2.3
Multiply each term in by to eliminate the fractions.
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Step 2.3.1
Multiply each term in by .
Step 2.3.2
Simplify the left side.
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Step 2.3.2.1
Simplify each term.
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Step 2.3.2.1.1
Multiply by by adding the exponents.
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Step 2.3.2.1.1.1
Move .
Step 2.3.2.1.1.2
Use the power rule to combine exponents.
Step 2.3.2.1.1.3
Combine the numerators over the common denominator.
Step 2.3.2.1.1.4
Add and .
Step 2.3.2.1.1.5
Divide by .
Step 2.3.2.1.2
Simplify .
Step 2.3.2.1.3
Cancel the common factor of .
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Step 2.3.2.1.3.1
Cancel the common factor.
Step 2.3.2.1.3.2
Rewrite the expression.
Step 2.3.3
Simplify the right side.
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Step 2.3.3.1
Multiply by .
Step 2.4
Solve the equation.
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Step 2.4.1
Subtract from both sides of the equation.
Step 2.4.2
Divide each term in by and simplify.
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Step 2.4.2.1
Divide each term in by .
Step 2.4.2.2
Simplify the left side.
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Step 2.4.2.2.1
Cancel the common factor of .
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Step 2.4.2.2.1.1
Cancel the common factor.
Step 2.4.2.2.1.2
Divide by .
Step 2.4.2.3
Simplify the right side.
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Step 2.4.2.3.1
Cancel the common factor of and .
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Step 2.4.2.3.1.1
Factor out of .
Step 2.4.2.3.1.2
Cancel the common factors.
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Step 2.4.2.3.1.2.1
Factor out of .
Step 2.4.2.3.1.2.2
Cancel the common factor.
Step 2.4.2.3.1.2.3
Rewrite the expression.
Step 2.4.2.3.2
Move the negative in front of the fraction.
Step 2.5
Exclude the solutions that do not make true.
Step 3
There are no values of in the domain of the original problem where the derivative is or undefined.
No critical points found
Step 4
Find where the derivative is undefined.
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Step 4.1
Convert expressions with fractional exponents to radicals.
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Step 4.1.1
Apply the rule to rewrite the exponentiation as a radical.
Step 4.1.2
Apply the rule to rewrite the exponentiation as a radical.
Step 4.1.3
Anything raised to is the base itself.
Step 4.1.4
Anything raised to is the base itself.
Step 4.2
Set the denominator in equal to to find where the expression is undefined.
Step 4.3
Solve for .
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Step 4.3.1
To remove the radical on the left side of the equation, square both sides of the equation.
Step 4.3.2
Simplify each side of the equation.
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Step 4.3.2.1
Use to rewrite as .
Step 4.3.2.2
Simplify the left side.
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Step 4.3.2.2.1
Simplify .
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Step 4.3.2.2.1.1
Multiply the exponents in .
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Step 4.3.2.2.1.1.1
Apply the power rule and multiply exponents, .
Step 4.3.2.2.1.1.2
Cancel the common factor of .
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Step 4.3.2.2.1.1.2.1
Cancel the common factor.
Step 4.3.2.2.1.1.2.2
Rewrite the expression.
Step 4.3.2.2.1.2
Simplify.
Step 4.3.2.3
Simplify the right side.
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Step 4.3.2.3.1
Raising to any positive power yields .
Step 4.4
Set the radicand in less than to find where the expression is undefined.
Step 4.5
The equation is undefined where the denominator equals , the argument of a square root is less than , or the argument of a logarithm is less than or equal to .
Step 5
After finding the point that makes the derivative equal to or undefined, the interval to check where is increasing and where it is decreasing is .
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
Rewrite as .
Step 6.2.1.2
Evaluate the exponent.
Step 6.2.1.3
Rewrite as .
Step 6.2.1.4
Simplify the denominator.
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Step 6.2.1.4.1
Rewrite as .
Step 6.2.1.4.2
Evaluate the exponent.
Step 6.2.1.4.3
Rewrite as .
Step 6.2.1.5
Multiply the numerator and denominator of by the conjugate of to make the denominator real.
Step 6.2.1.6
Multiply.
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Step 6.2.1.6.1
Combine.
Step 6.2.1.6.2
Simplify the denominator.
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Step 6.2.1.6.2.1
Raise to the power of .
Step 6.2.1.6.2.2
Raise to the power of .
Step 6.2.1.6.2.3
Use the power rule to combine exponents.
Step 6.2.1.6.2.4
Add and .
Step 6.2.1.6.2.5
Rewrite as .
Step 6.2.1.7
Move the negative one from the denominator of .
Step 6.2.1.8
Rewrite as .
Step 6.2.1.9
Multiply by .
Step 6.2.2
Subtract from .
Step 6.2.3
The final answer is .
Step 6.3
At the derivative is . Since this contains an imaginary number, the function does not exist on .
Function is not real on since is imaginary
Function is not real on since is imaginary
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
One to any power is one.
Step 7.2.1.2
Multiply by .
Step 7.2.1.3
One to any power is one.
Step 7.2.1.4
Divide by .
Step 7.2.2
Add and .
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:
Step 9