High School Math : Finding Second Derivative of a Function

Study concepts, example questions & explanations for High School Math

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Example Questions

Example Question #1 : Finding Second Derivative Of A Function

What is the second derivative of \(\displaystyle 2x^4+\frac{1}{2}x\)?

Possible Answers:

\(\displaystyle 24\)

\(\displaystyle 24x^{-2}\)

\(\displaystyle 24x^{2}\)

\(\displaystyle 0\)

\(\displaystyle 24x^{2}+\frac{1}{2x}\)

Correct answer:

\(\displaystyle 24x^{2}\)

Explanation:

To take the second derivative, we need to start with the first derivative.

To take the derivative of this equation, we can use the power rule. The power rule says that we lower the exponent of each variable by one and multiply that number by the original exponent.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(2x^4+\frac{1}{2}x)=(4*2x^{4-1})+(1*\frac{1}{2}x^{1-1})\)

Simplify.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(2x^4+\frac{1}{2}x)=(4*2x^{3})+(\frac{1}{2}x^{0})\)

Remember that anything to the zero power is equal to one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(2x^4+\frac{1}{2}x)=(8x^{3})+(\frac{1}{2}*1)\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(2x^4+\frac{1}{2}x)=8x^{3}+\frac{1}{2}\)

Now we repeat the process, but using \(\displaystyle 8x^3+\frac{1}{2}\) as our expression.

We're going to treat \(\displaystyle \frac{1}{2}\) as being \(\displaystyle \frac{1}{2}x^0\) since anything to the zero power is equal to one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(8x^{3}+\frac{1}{2})=(3*8x^{3-1})+(0*\frac{1}{2}x^{0-1})\)

Notice that \(\displaystyle (0*\frac{1}{2}x^{0-1})=0\) since anything times zero is zero.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(8x^{3}+\frac{1}{2})=(3*8x^{2})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(8x^{3}+\frac{1}{2})=24x^{2}\)

 

Example Question #42 : Calculus I — Derivatives

What is the second derivative of \(\displaystyle 3x+12\)?

Possible Answers:

\(\displaystyle 0\)

\(\displaystyle 3\)

\(\displaystyle x+8\)

\(\displaystyle \frac{3}{2}x^2\)

Undefined

Correct answer:

\(\displaystyle 0\)

Explanation:

To take the second derivative, we need to start with the first derivative.

To take the derivative of this equation, we can use the power rule. The power rule says that we lower the exponent of each variable by one and multiply that number by the original exponent.

We are going to treat \(\displaystyle 12\) as \(\displaystyle 12x^0\) since anything to the zero power is one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x+12)=(3x^{1-1})+(0*12x^{0-1})\)

Notice that \(\displaystyle (0*12x^{0-1})=0\) since anything times zero is zero.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x+12)=(3x^{1-1})\)

Simplify.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x+12)=(3x^{0})\)

As stated before, anything to the zero power is one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x+12)=3*1\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x+12)=3\)

Now we repeat the process but use \(\displaystyle 3\), or \(\displaystyle 3x^0\), as our expression.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x^0)=0*3x^{0-1}\)

As stated before, anything times zero is zero.

Therefore, \(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x^0)=0\).

Example Question #41 : Calculus I — Derivatives

What is the second derivative of \(\displaystyle 5x^2+12x\)?

Possible Answers:

\(\displaystyle 3\)

\(\displaystyle 10\)

\(\displaystyle 5\)

\(\displaystyle 10x+12\)

\(\displaystyle 11\)

Correct answer:

\(\displaystyle 10\)

Explanation:

To find the second derivative, first we need to start with the first derivative.

To find the first derivative, we can use the power rule. We lower the exponent on all the variables by one and multiply by the original variable.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(5x^2+12x)=(2*5x^{2-1})+(1*12x^{1-1})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(5x^2+12x)=(2*5x^{1})+(1*12x^{0})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(5x^2+12x)=10x^1+12x^0\)

Anything to the zero power is one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(5x^2+12x)=10x^1+12(1)\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(5x^2+12x)=10x+12\)

Now we repeat the process using \(\displaystyle 10x+12\) as our expression.

We're going to treat \(\displaystyle 12\) as \(\displaystyle 12x^0\).

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(10x+12)=(1*10x^{1-1})+(0*12x^{0-1})\)

Notice that \(\displaystyle (0*12x^{0-1})=0\) since anything times zero is zero.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(10x+12)=(1*10x^{1-1})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(10x+12)=(10x^{0})\)

As stated before, anything to the zero power is one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(10x+12)=10(1)\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(10x+12)=10\)

Example Question #42 : Calculus I — Derivatives

What is the second derivative of \(\displaystyle -8x^2+15\)?

Possible Answers:

\(\displaystyle 16x\)

\(\displaystyle 16\)

\(\displaystyle 17\)

\(\displaystyle -16\)

\(\displaystyle 31\)

Correct answer:

\(\displaystyle -16\)

Explanation:

To find the second derivative, we start by taking the first derivative.

To find the first derivative, we can use the power rule. We lower the exponent on all the variables by one and multiply by the original variable.

We're going to treat \(\displaystyle 15\) as \(\displaystyle 15x^0\) since anything to the zero power is one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(-8x^2+15)=(2*-8x^{2-1})+(0*15x^{0-1})\)

Notice that \(\displaystyle (0*15x^{0-1})=0\) since anything times zero is zero.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(-8x^2+15)=(2*-8x^{1})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(-8x^2+15)=-16x\)

Now we repeat the process, but using \(\displaystyle -16x\) as our expression.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(-16x)=1*-16x^{1-1}\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(-16x)=-16x^{0}\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(-16x)=-16\)

Example Question #5 : Finding Second Derivative Of A Function

What is the second derivative of \(\displaystyle x^3+2x^2+5\)?

Possible Answers:

\(\displaystyle \frac{2}{3}x+\frac{1}{4}\)

\(\displaystyle 3x^2+4x\)

\(\displaystyle 6\)

\(\displaystyle 6x+4\)

\(\displaystyle 6x\)

Correct answer:

\(\displaystyle 6x+4\)

Explanation:

To find the second derivative, we need to start by finding the first derivative.

To find the first derivative, we can use the power rule. To do that, we lower the exponent on the variables by one and multiply by the original exponent.

We're going to treat \(\displaystyle 5\) as \(\displaystyle 5x^0\) since anything to the zero power is one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(x^3+2x^2+5)=(3*x^{3-1})+(2*2x^{2-1})+(0*5x^{0-1})\)

Notice that \(\displaystyle (0*5x^{0-1}) =0\) since anything times zero is zero.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(x^3+2x^2+5)=(3*x^{3-1})+(2*2x^{2-1})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(x^3+2x^2+5)=(3*x^{2})+(2*2x^{1})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(x^3+2x^2+5)=3x^2+4x\)

Now we repeat the process but using \(\displaystyle 3x^2+4x\) as our expression.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x^2+4x)=(2*3x^{2-1})+(1*4x^{1-1})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x^2+4x)=(2*3x^{1})+(1*4x^{0})\)

Remember, anything to the zero power is one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x^2+4x)=(6x)+(4(1))\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(3x^2+4x)=6x+4\)

Example Question #1 : Finding Second Derivative Of A Function

What is the second derivative of \(\displaystyle 4x^2+\frac{2}{3}x\)?

Possible Answers:

\(\displaystyle 8x+\frac{2}{3}\)

\(\displaystyle 8\)

\(\displaystyle 3x\)

\(\displaystyle x\)

\(\displaystyle 2x\)

Correct answer:

\(\displaystyle 8\)

Explanation:

To find the second derivative, we need to start by finding the first derivative.

To find the first derivative for this problem, we can use the power rule. The power rule states that we lower the exponent of each of the variables by one and multiply by that original exponent.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(4x^2+\frac{2}{3}x)=(2*4x^{2-1})+(1*\frac{2}{3}x^{1-1})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(4x^2+\frac{2}{3}x)=(2*4x^{1})+(1*\frac{2}{3}x^{0})\)

Remember that anything to the zero power is one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(4x^2+\frac{2}{3}x)=(8x)+(1*\frac{2}{3}(1))\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(4x^2+\frac{2}{3}x)=8x+\frac{2}{3}\)

Now we repeat the process, but we use \(\displaystyle 8x+\frac{2}{3}\) as our expression.

For this problem, we're going to say that \(\displaystyle \frac{2}{3}=\frac{2}{3}x^0\) since, as stated before, anything to the zero power is one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(8x+\frac{2}{3})=(1*8x^{1-1})+(0*\frac{2}{3}x^{0-1})\)

Notice that \(\displaystyle (0*\frac{2}{3}x^{0-1})=0\) as anything times zero is zero.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(8x+\frac{2}{3})=(1*8x^{1-1})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(8x+\frac{2}{3})=(8x^{0})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(8x+\frac{2}{3})=8\)

Example Question #1 : Finding Second Derivative Of A Function

What is the second derivative of \(\displaystyle (x+6)^2\)?

Possible Answers:

\(\displaystyle 2\)

\(\displaystyle \frac{1}{2}\)

\(\displaystyle 2x+12\)

\(\displaystyle 2x\)

\(\displaystyle 6x+12\)

Correct answer:

\(\displaystyle 2\)

Explanation:

To find the second derivative, we need to start with the first derivative.

To solve for the first derivative, we're going to use the chain rule. The chain rule says that when taking the derivative of a nested function, your answer is the derivative of the outside times the derivative of the inside.

Mathematically, it would look like this: \(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}f(g(x))=f'(g(x))*g'(x)\)

Plug in our equations.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(x+6)^2=(2(x+6)^{1})*(1+0)\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(x+6)^2=(2(x+6))\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(x+6)^2=2x+12\)

From here, we can use our normal power rule to find the second derivative.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(2x+12)=(1*2x^{1-1})+(0*12x^{0-1})\)

Anything times zero is zero.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(2x+12)=(1*2x^{1-1})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(2x+12)=(2x^{0})\)

Anything to the zero power is one.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(2x+12)=2\)

Example Question #2121 : High School Math

What is the second derivative of \(\displaystyle 4x^2+5x-3\)?

Possible Answers:

\(\displaystyle y=32x+5x^2\)

\(\displaystyle y=8\)

\(\displaystyle y=3\)

\(\displaystyle y=16x\)

\(\displaystyle y=8x\)

Correct answer:

\(\displaystyle y=8\)

Explanation:

To find the second derivative, we need to find the first derivative first. To find the first derivative, we can use the power rule.

For each variable, multiply by the exponent and reduce the exponent by one:

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(4x^2+5x-3)=(2*4x^{2-1})+(1*5x^{1-1})-(0*3x^0-1)\)

Treat \(\displaystyle 3\) as \(\displaystyle 3x^0\) since anything to the zero power is one.

Remember, anything times zero is zero.

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(4x^2+5x-3)=(8x^{1})+(5x^{0})-0\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(4x^2+5x-3)=8x+5\)

Now follow the same process but for \(\displaystyle 8x+5\).

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(8x+5)=(1*8x^{1-1})+(0*5x^{0-1})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(8x+5)=(1*8x^{0})\)

\(\displaystyle \frac{\mathrm{d} }{\mathrm{d} x}(8x+5)=8\)

Therefore the second derivative will be the line \(\displaystyle y=8\).

Example Question #291 : Computation Of The Derivative

Let \(\displaystyle f(x)=sin(x)-cos(x)\).

Find the second derivative of \(\displaystyle f(x)\).

Possible Answers:

\(\displaystyle f''(x)=sin^2(x)+cos^2(x)\)

\(\displaystyle f''(x)=sin(x)+cos(x)\)

\(\displaystyle f''(x)=sin(x)-cos(x)\)

\(\displaystyle f''(x)=sin^2(x)-cos^2(x)\)

\(\displaystyle f''(x)=cos(x)-sin(x)\)

Correct answer:

\(\displaystyle f''(x)=cos(x)-sin(x)\)

Explanation:

The second derivative is just the derivative of the first derivative. So first we find the first derivative of \(\displaystyle f(x)\). Remember the derivative of \(\displaystyle \sin x\) is \(\displaystyle \cos x\), and the derivative for \(\displaystyle \cos x\) is \(\displaystyle -\sin x\).

 \(\displaystyle f'(x)= cos(x)+sin(x)\)

 

Then to get the second derivative, we just derive this function again. So

\(\displaystyle f''(x)=-sin(x)+cos(x)=cos(x)-sin(x)\)

Example Question #1 : Finding Second Derivative Of A Function

Define \(\displaystyle f (x) = 6x^{3} - 12x^{2} + 4x -8\).

What is \(\displaystyle f ' ' (x)\)?

Possible Answers:

\(\displaystyle f ''(x) = 18x - 24\)

\(\displaystyle f ' '(x) = 36x\)

\(\displaystyle f ' '(x) = 36x - 24\)

\(\displaystyle f ' '(x) = 6x - 1 2\)

\(\displaystyle f ' '(x) = 18\)

Correct answer:

\(\displaystyle f ' '(x) = 36x - 24\)

Explanation:

Take the derivative \(\displaystyle f'\) of \(\displaystyle f\), then take the derivative of \(\displaystyle f'\).

\(\displaystyle f (x) = 6x^{3} - 12x^{2} + 4x -8\)

 

\(\displaystyle f '(x) = 3 \cdot 6x^{3-1} - 2 \cdot 12x^{2-1} + 4 -0\)

\(\displaystyle f '(x) = 18x^{2} - 24x+ 4\)

 

\(\displaystyle f ' '(x) = 2 \cdot 18x^{2-1} - 24+ 0\)

\(\displaystyle f ' '(x) = 36x - 24\)

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