Calculus 1 : Functions

Study concepts, example questions & explanations for Calculus 1

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Example Questions

Example Question #1041 : Differential Functions

Find the derivative.

\(\displaystyle -4x^3\)

Possible Answers:

\(\displaystyle -12x^2\)

\(\displaystyle 4x^3\)

\(\displaystyle -4x^2\)

\(\displaystyle 12x^2\)

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 : How To Find Differential Functions

Find the derivative. 

\(\displaystyle 4x-3\)

Possible Answers:

\(\displaystyle 4x\)

\(\displaystyle -4x\)

\(\displaystyle 1\)

\(\displaystyle 4\)

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 #853 : Other Differential Functions

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

\(\displaystyle 8x^2-4x+4\)

Possible Answers:

\(\displaystyle 16x-4\)

\(\displaystyle 8x+4\)

\(\displaystyle 8x-4\)

\(\displaystyle 16x+4\)

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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