Calculus 1 : Functions

Study concepts, example questions & explanations for Calculus 1

varsity tutors app store varsity tutors android store

Example Questions

Example Question #1321 : Functions

Find the particular solution given \displaystyle y\left(-\frac{1}{2}\right)=-\frac{1}{4}

\displaystyle \frac{\mathrm{d} y}{\mathrm{d} x}=6x^2y^2

Possible Answers:

\displaystyle -\frac{1}{y}=2x^3+\frac{1}{2}

\displaystyle -\frac{1}{3y^3}=2x^3+\frac{259}{12}

\displaystyle -\frac{1}{y}=2x^3+\frac{1}{8}

\displaystyle -\frac{1}{y}=2x^3+\frac{17}{4}

Correct answer:

\displaystyle -\frac{1}{y}=2x^3+\frac{17}{4}

Explanation:

The first thing we must do is rewrite the equation:

\displaystyle \left(\frac{1}{y^2}\right)dy=(6x^2)dx

We can then find the integrals:

\displaystyle \int \left(\frac{1}{y^2}\right)dy=\int (6x^2)dx

  The integrals are as follows:

\displaystyle \int \left(\frac{1}{y^2}\right)dy=-\frac{1}{y}

\displaystyle \int (6x^2)dx=2x^3

We're left with:

\displaystyle -\frac{1}{y}=2x^3+c

We then plug in the initial condition and solve for \displaystyle c.

\displaystyle -\frac{1}{(-\frac{1}{4})}=2\left(-\frac{1}{2}\right)^3+c

\displaystyle 4=-\frac{1}{4}+c

\displaystyle c=\frac{17}{4}

The particular solution is then:

\displaystyle -\frac{1}{y}=2x^3+\frac{17}{4}

Example Question #1322 : Functions

Find the particular solution given \displaystyle y(4)=\frac{256}{9}.

\displaystyle \frac{\mathrm{d} y}{\mathrm{d} x}=\sqrt{xy}

Possible Answers:

\displaystyle \sqrt{y}=\frac{3}{2}(x)^\frac{3}{2}

\displaystyle \sqrt{y}=\frac{2}{3}(x)^\frac{3}{2} -\frac{32}{3}

\displaystyle 2\sqrt{y}=\frac{2}{3}(x)^\frac{3}{2}+\frac{16}{3}

\displaystyle y=x^\frac{3}{2}

Correct answer:

\displaystyle 2\sqrt{y}=\frac{2}{3}(x)^\frac{3}{2}+\frac{16}{3}

Explanation:

Remember: \displaystyle \sqrt{xy}=(\sqrt{x} ) (\sqrt{y})

 

The first thing we must do is rewrite the equation:

\displaystyle \left(\frac{1}{\sqrt{y}}\right)dy=(\sqrt{x})dx

We can then find the integrals:

\displaystyle \int \left(\frac{1}{\sqrt{y}}\right)dy=\int (\sqrt{x})dx

The integrals are as follows:

\displaystyle \int \left(\frac{1}{\sqrt{y}}\right)dy= \int y^{-1/2}dy=\frac{y^{1/2}}{\frac{1}{2}}=2y^{1/2}=2\sqrt{y}

\displaystyle \int (\sqrt{x})dx=\frac{2}{3}(x^{\frac{3}{2}})

We're left with:

\displaystyle 2\sqrt{y}=\frac{2}{3}(x)^{\frac{3}{2}}+c

We then plug in the initial condition and solve for \displaystyle c.

\displaystyle 2\sqrt{\frac{256}{9}}= \frac{2}{3}(4)^{\frac{3}{2}}+c

\displaystyle \frac{32}{3}=\frac{16}{3}+c

\displaystyle c=\frac{16}{3}

The particular solution is then:

\displaystyle 2\sqrt{y}=\frac{2}{3}(x)^{\frac{3}{2}}+\frac{16}{3}

Example Question #22 : Differential Equations

Find the particular solution given \displaystyle y(1)=0

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

Possible Answers:

\displaystyle \frac{1}{3}y^3+y^4=x^5

\displaystyle y^3+\frac{1}{4}y^4=\frac{1}{5}x^5-1

\displaystyle \frac{1}{3}y^3+y^4=x^5-1

\displaystyle \frac{1}{3}y^3+y^4=x^5+\frac{4}{3}

Correct answer:

\displaystyle \frac{1}{3}y^3+y^4=x^5-1

Explanation:

The first thing we must do is rewrite the equation:

\displaystyle (y^2+4y^3)dy=(5x^4)dx

We can then find the integrals:

\displaystyle \int (y^2+4y^3)dy=\int (5x^4)dx

The integrals are as follows:

\displaystyle \int (y^2+4y^3)dy=\frac{1}{3}y^3+y^4

\displaystyle \int (5x^4)dx=x^5

We're left with

\displaystyle \frac{1}{3}y^3+y^4=x^5+c

We plug in the initial condition and solve for \displaystyle c.

\displaystyle \frac{1}{3}(0)^3+(0)^4=(1)^5+c

\displaystyle c=-1

The particular solution is then:

\displaystyle \frac{1}{3}y^3+y^4=x^5-1

Example Question #23 : Differential Equations

Find the particular solution given \displaystyle y(2)=1

\displaystyle \frac{\mathrm{d} y}{\mathrm{d} x}=\frac{2x^3+3x^2-x+7}{y^5+3y^2-2y}

Possible Answers:

\displaystyle \frac{1}{6}y^6+y^3-y^2=\frac{1}{2}x^4+x^3-\frac{1}{2}x^2+7x-\frac{167}{6}

\displaystyle y^6+y^3-y^2=\frac{1}{8}x^4+x^3-\frac{1}{2}x^2-7

\displaystyle \frac{1}{6}y^6+y^3-y^2=\frac{1}{2}x^4+x^3-\frac{1}{2}x^2+7x

\displaystyle \frac{1}{6}y^6+y^3-y^2=\frac{1}{2}x^4+x^3-\frac{1}{2}x^2+7x-28

Correct answer:

\displaystyle \frac{1}{6}y^6+y^3-y^2=\frac{1}{2}x^4+x^3-\frac{1}{2}x^2+7x-\frac{167}{6}

Explanation:

The first thing we must do is rewrite the equation:

\displaystyle ({y^5+3y^2-2y})dy=({2x^3+3x^2-x+7})dx

We can then find the integrals:

\displaystyle ({y^5+3y^2-2y})dy=({2x^3+3x^2-x+7})dx

The integrals are as follows:

\displaystyle \int ({y^5+3y^2-2y})dy=\frac{1}{6}y^6+y^3-y^2

 

\displaystyle \int ({2x^3+3x^2-x+7})dx=\frac{1}{2}x^4+x^3-\frac{1}{2}x^2+7x

We're left with

\displaystyle \frac{1}{6}y^6+y^3-y^2=\frac{1}{2}x^4+x^3-\frac{1}{2}x^2+7x+c

Plugging in the initial conditions and solving for c gives us:

\displaystyle \frac{1}{6}+1-1=8-8-2+14+c

\displaystyle c=-\frac{167}{6}

The particular solution is then,

\displaystyle \frac{1}{6}y^6+y^3-y^2=\frac{1}{2}x^4+x^3-\frac{1}{2}x^2+7x-\frac{167}{6}

Example Question #1323 : Functions

Differentiate the polynomial.

\displaystyle x^{2}+4x+1

Possible Answers:

\displaystyle x+1

\displaystyle 2x+4

\displaystyle x^{2}+1

\displaystyle 4x+1

\displaystyle 2x^{2}+4x

Correct answer:

\displaystyle 2x+4

Explanation:

Using the power rule, we can differentiate our first term reducing the power by one and multiplying our term by the original power. \displaystyle x^{2}, will thus become \displaystyle 2x. The second term \displaystyle 4x, will thus become \displaystyle 4. The last term is a constant value, so according to the power rule this term will become \displaystyle 0.

Example Question #31 : Differential Equations

Differentiate the expression.

\displaystyle e^{6x}

Possible Answers:

\displaystyle 6xe

\displaystyle 6e

\displaystyle 6x

\displaystyle 6e^{6x}

\displaystyle e^{6x}

Correct answer:

\displaystyle 6e^{6x}

Explanation:

We will use the fact that \displaystyle e^{au} = ae^{au} to differentiate. Let \displaystyle a=6 and \displaystyle u=x. Substituing our values we can see the derivative will be \displaystyle 6e^{6x}.

Example Question #272 : Equations

Differentiate the expression.

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

Possible Answers:

\displaystyle 2x\sin(x)

\displaystyle x^2

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

\displaystyle 2x\cos(x)

\displaystyle x\cos(x)

Correct answer:

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

Explanation:

Using the product rule, we determine the derivative of \displaystyle f(x)\cdot g(x) = {f}'(x)\cdot g(x) + f(x)\cdot {g}'(x))
Let \displaystyle f(x) = x^{2} and \displaystyle g(x) = \sin(x). We can see that \displaystyle f{}'(x) = 2x and \displaystyle g{}'(x) = \cos(x).

Plugging in our values into the product rule formula, we are left with the final derivative of \displaystyle x (2 \sin(x)+x \cos(x)).

Example Question #1324 : Functions

Differentiate the value.

\displaystyle 74

Possible Answers:

\displaystyle 74x^{2}

\displaystyle 0

\displaystyle 1

\displaystyle 74

\displaystyle 74x

Correct answer:

\displaystyle 0

Explanation:

According to the power rule, whenever we differentiate a constant value it will reduce to zero. Since the only term of our function is a constant, we can only differentiate  \displaystyle 74 \rightarrow 0.

Example Question #272 : Equations

Find \displaystyle {f}'(x).

\displaystyle f(x) = e^{2x^{2}}

Possible Answers:

\displaystyle 4xe^{2x^{2}}

\displaystyle e^{4x}

\displaystyle 2e^{x^{2}}

\displaystyle 4e^{x}

\displaystyle e^{2x^{2}}

Correct answer:

\displaystyle 4xe^{2x^{2}}

Explanation:

Using the chain rule, we will differentiate the exponent of our exponential function, and then multiply our original function. Differentiating our exponent with the power rule will yield \displaystyle 4x. Using the chain rule we will multiply this by our original function resulting in \displaystyle 4xe^{2x^{2}}.

Example Question #1325 : Functions

Find \displaystyle {f}'(x).

\displaystyle f(x) = x^{2}-4

Possible Answers:

\displaystyle x^{2}

\displaystyle 2x

\displaystyle 4x

\displaystyle 2x-4

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

Correct answer:

\displaystyle 2x

Explanation:

Using the power rule, we can differentiate our first term reducing the power by one and multiplying our term by the original power. \displaystyle x^{2}, will thus become \displaystyle 2x. The second term is a constant value, so according to the power rule this term will become \displaystyle 0.

Learning Tools by Varsity Tutors