Calculus 1 : Functions

Study concepts, example questions & explanations for Calculus 1

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Example Questions

Example Question #851 : Other Differential Functions

Find the derivative.

\displaystyle -4x^3

Possible Answers:

\displaystyle -4x^2

\displaystyle -12x^2

\displaystyle 12x^2

\displaystyle 4x^3

Correct answer:

\displaystyle -12x^2

Explanation:

Use the power rule to find the derivative.

The power rule states,

\displaystyle \frac{d}{dx}x^n=nx^{n-1}.

Applying this rule to the function in the problem results in the following.

\displaystyle \frac{d}{dx}(-4x^3)=3(-4)x^{3-1}=-12x^2

Example Question #852 : Other Differential Functions

Find the derivative. 

\displaystyle 4x-3

Possible Answers:

\displaystyle -4x

\displaystyle 1

\displaystyle 4

\displaystyle 4x

Correct answer:

\displaystyle 4

Explanation:

Use the power rule to find the derivative. 

The power rule states,

\displaystyle \frac{d}{dx}x^n=nx^{n-1}.

Applying this rule to each term of the function results in the following.

\displaystyle \frac{d}{dx}4x=4

\displaystyle \frac{d}{dx}-3=0

Thus, the derivative is 4.

Example Question #1043 : Differential Functions

What is the equation for the slope of the tangent line to:

\displaystyle 8x^2-4x+4

Possible Answers:

\displaystyle 8x-4

\displaystyle 8x+4

\displaystyle 16x-4

\displaystyle 16x+4

Correct answer:

\displaystyle 16x-4

Explanation:

To find the equation for the slope of the tangent line, find the derivative.

To find the derivative, use the power rule.

The power rule states,

\displaystyle \frac{d}{dx}x^n=nx^{n-1}.

Applying the power rule to each term in the function results in,

\displaystyle \frac{d}{dx}8x^2=16x

\displaystyle \frac{d}{dx}-4x=-4

\displaystyle \frac{d}{dx}4=0.

Thus, the derivative is \displaystyle 16x-4.

Example Question #854 : Other Differential Functions

Find the derivative when \displaystyle x=3.

\displaystyle x^3+5x^2

Possible Answers:

\displaystyle 57

\displaystyle 40

\displaystyle 67

\displaystyle 70

Correct answer:

\displaystyle 57

Explanation:

Use the power rule to find the derivative.

The power rule states,

\displaystyle \frac{d}{dx}x^n=nx^{n-1}.

Applying the power rule to each term within the function results in the following.

\displaystyle \frac{d}{dx}x^3=3x^2

\displaystyle \frac{d}{dx}5x^2=10x

Thus, the derivative is \displaystyle 3x^2+10x

Now, substitute \displaystyle 3 for \displaystyle x.

\displaystyle 3(3^2)+10(3)=57

Example Question #855 : Other Differential Functions

Find the derivative when \displaystyle x=2.

\displaystyle 5x^2-3x

Possible Answers:

\displaystyle 20

\displaystyle 14

\displaystyle 12

\displaystyle 17

Correct answer:

\displaystyle 17

Explanation:

First, use the power rule to find the derivative.

The power rule states,

\displaystyle \frac{d}{dx}x^n=nx^{n-1}.

Applying the power rule to each term in the function results in the following.

\displaystyle \frac{d}{dx}5x^2=10x

\displaystyle \frac{d}{dx}-3x=-3

Thus, the derivative is \displaystyle 10x-3.

Now, substitute 2 for x.

\displaystyle 10(2)-3=17.

Example Question #856 : Other Differential Functions

Find the derivative.

\displaystyle 2x\cos (x)

Possible Answers:

\displaystyle -2x\sin(x) -2\cos (x)

\displaystyle 2x\sin(x) -2\cos (x)

\displaystyle 2x\sin(x) +2\cos (x)

\displaystyle -2x\sin(x) +2\cos (x)

Correct answer:

\displaystyle -2x\sin(x) +2\cos (x)

Explanation:

Use the product rule to find the derivative.

The product rule states,

\displaystyle \frac{d}{dx}f(x)g(x)=f(x)g'(x)+g(x)f'(x).

Given,

\displaystyle f(x)=2x

\displaystyle g(x)=cos(x)

and recalling the trigonometry derivative for cosine is,

\displaystyle \frac{d}{dx}cos(x)=-sin(x)

the derivatives are as follows.

\displaystyle f'(x)=1\cdot 2x^{1-1}=2

\displaystyle g'(x)=-sin(x)

Therefore, using the product rule the derivative becomes,

\displaystyle 2x(-\sin x)+2\cos (x).

 

Example Question #857 : Other Differential Functions

Find the derivative. 

\displaystyle 2x^4-x^3

Possible Answers:

\displaystyle 8x^3+x^2

\displaystyle 8x^3-x^2

\displaystyle 8x^3+3x^2

\displaystyle 8x^3-3x^2

Correct answer:

\displaystyle 8x^3-3x^2

Explanation:

Use the power rule to find the derivative.

The power rule states,

\displaystyle \frac{d}{dx}x^n=nx^{n-1}.

Applying the power rule to each term in the function results in the following.

\displaystyle \frac{d}{dx}2x^4=8x^3

\displaystyle \frac{d}{dx}(-x^3)=-3x^2.

Thus, the derivative is \displaystyle 8x^3-3x^2.

Example Question #861 : How To Find Differential Functions

Find the derivative. 

\displaystyle 5x\sin (x)

Possible Answers:

\displaystyle 5x\cos (x)-5\sin (x)

\displaystyle 5x\cos (x)-\sin (x)

\displaystyle 5x\cos (x)+5\sin (x)

\displaystyle x\cos (x)+\sin (x)

Correct answer:

\displaystyle 5x\cos (x)+5\sin (x)

Explanation:

Use the product rule to find the derivative.

The product rule states,

\displaystyle \frac{d}{dx}f(x)g(x)=f(x)g'(x)+g(x)f'(x).

Given,

\displaystyle f(x)=5x

\displaystyle g(x)=sin(x)

and recalling the trigonometry derivative for sine is,

\displaystyle \frac{d}{dx}sin(x)=cos(x)

the derivative becomes,

\displaystyle 5x\cos (x)+5\sin (x).

 

Example Question #862 : How To Find Differential Functions

Find the derivative at \displaystyle x=6

\displaystyle 4x^2

Possible Answers:

\displaystyle 36

\displaystyle 60

\displaystyle 24

\displaystyle 48

Correct answer:

\displaystyle 48

Explanation:

First, find the derivative using the power rule.

The power rule states,

\displaystyle \frac{d}{dx}x^n=nx^{n-1}.

Applying the power rule results in the following.

\displaystyle \frac{d}{dx}4x^2=8x

Now, substitute 6 for x.

\displaystyle 8(6)=48.

Example Question #863 : How To Find Differential Functions

Find the derivative. 

\displaystyle 9x^2+7x-8

Possible Answers:

\displaystyle 18x+7

\displaystyle 18x-7

\displaystyle 9x^2+7x

\displaystyle 9x^2-7x

Correct answer:

\displaystyle 18x+7

Explanation:

Use the power rule to find the derivative. 

The power rule states,

\displaystyle \frac{d}{dx}x^n=nx^{n-1}.

Applying the power rule to each term in the function results in the following.

\displaystyle \frac{d}{dx}9x^2=18x

\displaystyle \frac{d}{dx}7x=7

\displaystyle \frac{d}{dx}(-8)=0

Thus, the derivative is \displaystyle 18x+7.

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