Calculus Examples

Find the Concavity f(x)=x^(1/3)(x+4)
Step 1
Find the values where the second derivative is equal to .
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Step 1.1
Find the second derivative.
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Step 1.1.1
Find the first derivative.
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Step 1.1.1.1
Differentiate using the Product Rule which states that is where and .
Step 1.1.1.2
Differentiate.
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Step 1.1.1.2.1
By the Sum Rule, the derivative of with respect to is .
Step 1.1.1.2.2
Differentiate using the Power Rule which states that is where .
Step 1.1.1.2.3
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.1.2.4
Simplify the expression.
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Step 1.1.1.2.4.1
Add and .
Step 1.1.1.2.4.2
Multiply by .
Step 1.1.1.2.5
Differentiate using the Power Rule which states that is where .
Step 1.1.1.3
To write as a fraction with a common denominator, multiply by .
Step 1.1.1.4
Combine and .
Step 1.1.1.5
Combine the numerators over the common denominator.
Step 1.1.1.6
Simplify the numerator.
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Step 1.1.1.6.1
Multiply by .
Step 1.1.1.6.2
Subtract from .
Step 1.1.1.7
Move the negative in front of the fraction.
Step 1.1.1.8
Combine and .
Step 1.1.1.9
Move to the denominator using the negative exponent rule .
Step 1.1.1.10
Simplify.
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Step 1.1.1.10.1
Apply the distributive property.
Step 1.1.1.10.2
Combine terms.
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Step 1.1.1.10.2.1
Combine and .
Step 1.1.1.10.2.2
Move to the numerator using the negative exponent rule .
Step 1.1.1.10.2.3
Multiply by by adding the exponents.
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Step 1.1.1.10.2.3.1
Multiply by .
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Step 1.1.1.10.2.3.1.1
Raise to the power of .
Step 1.1.1.10.2.3.1.2
Use the power rule to combine exponents.
Step 1.1.1.10.2.3.2
Write as a fraction with a common denominator.
Step 1.1.1.10.2.3.3
Combine the numerators over the common denominator.
Step 1.1.1.10.2.3.4
Subtract from .
Step 1.1.1.10.2.4
Combine and .
Step 1.1.1.10.2.5
To write as a fraction with a common denominator, multiply by .
Step 1.1.1.10.2.6
Combine and .
Step 1.1.1.10.2.7
Combine the numerators over the common denominator.
Step 1.1.1.10.2.8
Move to the left of .
Step 1.1.1.10.2.9
Add and .
Step 1.1.2
Find the second derivative.
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Step 1.1.2.1
By the Sum Rule, the derivative of with respect to is .
Step 1.1.2.2
Evaluate .
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Step 1.1.2.2.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.2.2.2
Differentiate using the Power Rule which states that is where .
Step 1.1.2.2.3
To write as a fraction with a common denominator, multiply by .
Step 1.1.2.2.4
Combine and .
Step 1.1.2.2.5
Combine the numerators over the common denominator.
Step 1.1.2.2.6
Simplify the numerator.
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Step 1.1.2.2.6.1
Multiply by .
Step 1.1.2.2.6.2
Subtract from .
Step 1.1.2.2.7
Move the negative in front of the fraction.
Step 1.1.2.2.8
Combine and .
Step 1.1.2.2.9
Multiply by .
Step 1.1.2.2.10
Multiply by .
Step 1.1.2.2.11
Move to the denominator using the negative exponent rule .
Step 1.1.2.3
Evaluate .
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Step 1.1.2.3.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.2.3.2
Rewrite as .
Step 1.1.2.3.3
Differentiate using the chain rule, which states that is where and .
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Step 1.1.2.3.3.1
To apply the Chain Rule, set as .
Step 1.1.2.3.3.2
Differentiate using the Power Rule which states that is where .
Step 1.1.2.3.3.3
Replace all occurrences of with .
Step 1.1.2.3.4
Differentiate using the Power Rule which states that is where .
Step 1.1.2.3.5
Multiply the exponents in .
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Step 1.1.2.3.5.1
Apply the power rule and multiply exponents, .
Step 1.1.2.3.5.2
Multiply .
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Step 1.1.2.3.5.2.1
Combine and .
Step 1.1.2.3.5.2.2
Multiply by .
Step 1.1.2.3.5.3
Move the negative in front of the fraction.
Step 1.1.2.3.6
To write as a fraction with a common denominator, multiply by .
Step 1.1.2.3.7
Combine and .
Step 1.1.2.3.8
Combine the numerators over the common denominator.
Step 1.1.2.3.9
Simplify the numerator.
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Step 1.1.2.3.9.1
Multiply by .
Step 1.1.2.3.9.2
Subtract from .
Step 1.1.2.3.10
Move the negative in front of the fraction.
Step 1.1.2.3.11
Combine and .
Step 1.1.2.3.12
Combine and .
Step 1.1.2.3.13
Multiply by by adding the exponents.
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Step 1.1.2.3.13.1
Move .
Step 1.1.2.3.13.2
Use the power rule to combine exponents.
Step 1.1.2.3.13.3
Combine the numerators over the common denominator.
Step 1.1.2.3.13.4
Subtract from .
Step 1.1.2.3.13.5
Move the negative in front of the fraction.
Step 1.1.2.3.14
Move to the denominator using the negative exponent rule .
Step 1.1.2.3.15
Multiply by .
Step 1.1.2.3.16
Multiply by .
Step 1.1.2.3.17
Multiply by .
Step 1.1.3
The second derivative of with respect to is .
Step 1.2
Set the second derivative equal to then solve the equation .
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Step 1.2.1
Set the second derivative equal to .
Step 1.2.2
Find the LCD of the terms in the equation.
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Step 1.2.2.1
Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.
Step 1.2.2.2
Since contains both numbers and variables, there are two steps to find the LCM. Find LCM for the numeric part then find LCM for the variable part .
Step 1.2.2.3
The LCM is the smallest positive number that all of the numbers divide into evenly.
1. List the prime factors of each number.
2. Multiply each factor the greatest number of times it occurs in either number.
Step 1.2.2.4
has factors of and .
Step 1.2.2.5
The number is not a prime number because it only has one positive factor, which is itself.
Not prime
Step 1.2.2.6
The LCM of is the result of multiplying all prime factors the greatest number of times they occur in either number.
Step 1.2.2.7
Multiply by .
Step 1.2.2.8
The LCM of is the result of multiplying all prime factors the greatest number of times they occur in either term.
Step 1.2.2.9
The LCM for is the numeric part multiplied by the variable part.
Step 1.2.3
Multiply each term in by to eliminate the fractions.
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Step 1.2.3.1
Multiply each term in by .
Step 1.2.3.2
Simplify the left side.
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Step 1.2.3.2.1
Simplify each term.
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Step 1.2.3.2.1.1
Rewrite using the commutative property of multiplication.
Step 1.2.3.2.1.2
Cancel the common factor of .
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Step 1.2.3.2.1.2.1
Cancel the common factor.
Step 1.2.3.2.1.2.2
Rewrite the expression.
Step 1.2.3.2.1.3
Cancel the common factor of .
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Step 1.2.3.2.1.3.1
Factor out of .
Step 1.2.3.2.1.3.2
Cancel the common factor.
Step 1.2.3.2.1.3.3
Rewrite the expression.
Step 1.2.3.2.1.4
Divide by .
Step 1.2.3.2.1.5
Simplify.
Step 1.2.3.2.1.6
Cancel the common factor of .
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Step 1.2.3.2.1.6.1
Move the leading negative in into the numerator.
Step 1.2.3.2.1.6.2
Cancel the common factor.
Step 1.2.3.2.1.6.3
Rewrite the expression.
Step 1.2.3.3
Simplify the right side.
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Step 1.2.3.3.1
Multiply .
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Step 1.2.3.3.1.1
Multiply by .
Step 1.2.3.3.1.2
Multiply by .
Step 1.2.4
Solve the equation.
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Step 1.2.4.1
Add to both sides of the equation.
Step 1.2.4.2
Divide each term in by and simplify.
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Step 1.2.4.2.1
Divide each term in by .
Step 1.2.4.2.2
Simplify the left side.
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Step 1.2.4.2.2.1
Cancel the common factor of .
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Step 1.2.4.2.2.1.1
Cancel the common factor.
Step 1.2.4.2.2.1.2
Divide by .
Step 1.2.4.2.3
Simplify the right side.
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Step 1.2.4.2.3.1
Divide by .
Step 2
Find the domain of .
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Step 2.1
Convert expressions with fractional exponents to radicals.
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Step 2.1.1
Apply the rule to rewrite the exponentiation as a radical.
Step 2.1.2
Anything raised to is the base itself.
Step 2.2
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.
Interval Notation:
Set-Builder Notation:
Interval Notation:
Set-Builder Notation:
Step 3
Create intervals around the -values where the second derivative is zero or undefined.
Step 4
Substitute any number from the interval into the second derivative and evaluate to determine the concavity.
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Step 4.1
Replace the variable with in the expression.
Step 4.2
Simplify the expression.
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Step 4.2.1
Rewrite as .
Step 4.2.2
Apply the power rule and multiply exponents, .
Step 4.3
Cancel the common factor of .
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Step 4.3.1
Cancel the common factor.
Step 4.3.2
Rewrite the expression.
Step 4.4
Simplify the expression.
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Step 4.4.1
Raising to any positive power yields .
Step 4.4.2
Multiply by .
Step 4.4.3
The expression contains a division by . The expression is undefined.
Step 4.5
The expression contains a division by . The expression is undefined.
Step 4.6
The graph is concave up on the interval because is positive.
Concave up on since is positive
Concave up on since is positive
Step 5
Substitute any number from the interval into the second derivative and evaluate to determine the concavity.
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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
Move to the numerator using the negative exponent rule .
Step 5.2.1.2
Multiply by by adding the exponents.
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Step 5.2.1.2.1
Multiply by .
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Step 5.2.1.2.1.1
Raise to the power of .
Step 5.2.1.2.1.2
Use the power rule to combine exponents.
Step 5.2.1.2.2
Write as a fraction with a common denominator.
Step 5.2.1.2.3
Combine the numerators over the common denominator.
Step 5.2.1.2.4
Subtract from .
Step 5.2.2
The final answer is .
Step 5.3
The graph is concave up on the interval because is positive.
Concave up on since is positive
Concave up on since is positive
Step 6
The graph is concave down when the second derivative is negative and concave up when the second derivative is positive.
Concave up on since is positive
Concave up on since is positive
Step 7