Calculus 1 : How to find solutions to differential equations

Study concepts, example questions & explanations for Calculus 1

varsity tutors app store varsity tutors android store

Example Questions

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 #272 : Equations

Differentiate the value.

\displaystyle 74

Possible Answers:

\displaystyle 1

\displaystyle 74

\displaystyle 0

\displaystyle 74x^{2}

\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 #273 : Equations

Find \displaystyle {f}'(x).

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

Possible Answers:

\displaystyle 4x

\displaystyle x^{2}

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

\displaystyle 2x-4

\displaystyle 2x

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.

Example Question #32 : Differential Equations

Differentiate the logarithm. 

\displaystyle \ln(4x)

Possible Answers:

\displaystyle \frac{1}{4x}

\displaystyle 4\ln(4x)

\displaystyle 0

\displaystyle 4x

\displaystyle \frac{1}{x}

Correct answer:

\displaystyle \frac{1}{x}

Explanation:

Using the chain rule, we will determine the derivative of our function will be \displaystyle \frac{d\log(u)}{du}\cdot \frac{du}{dx}.

The derivative of the log function is \displaystyle \frac{1}{x}, and our second term of the chain rule will cancel out \displaystyle \frac{1}{4x}\cdot 4=\frac{4}{4x}=\frac{1}{x}.

Thus our derivative will be \displaystyle \frac{1}{x}.

Example Question #32 : Differential Equations

Differentiate the polynomial.

\displaystyle x^{4}+3x^{3}+4x

Possible Answers:

\displaystyle 3x^{3}+4x^{2}

\displaystyle 4x^{3}+9x^{2}+4

\displaystyle 4x^{3}+9x^{2}

\displaystyle x^{3}+3x^{2}+4

\displaystyle x^2+4x+7

Correct answer:

\displaystyle 4x^{3}+9x^{2}+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^{4}, will thus become \displaystyle 4x^{3}. The second term \displaystyle 3x^{3}, will thus become \displaystyle 9x^{2}. The last term is \displaystyle 4x, will reduce to \displaystyle 4.

Example Question #37 : Differential Equations

Find \displaystyle {f}'(x).

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

Possible Answers:

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

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

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

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

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

Correct answer:

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

Explanation:

According to the quotient rule, the derivative of ,

\displaystyle \frac{f(x)}{g(x)} = \frac{{f}'(x)g(x) - f(x){g}'(x))}{(g(x))^{2}}.

We will let \displaystyle f(x) = e^{x} , f{}'(x) = e^{x} , g(x) = x^{2} and \displaystyle g{}'(x) = 2x
Plugging all of our values into the quotient rule formula we come to a final solution of :

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

Example Question #281 : Equations

Differentiate the polynomial.

\displaystyle x^{3}+3x^{2}

Possible Answers:

\displaystyle 3x^{2}+6x

\displaystyle 3x^{4}+6x^{3}

\displaystyle 9x

\displaystyle x^{3}+3

\displaystyle 3x^{3}+6x

Correct answer:

\displaystyle 3x^{2}+6x

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^{3}, will thus become \displaystyle 3x^{2}. The second term \displaystyle 3x^{2}, will thus become \displaystyle 6x.

Example Question #24 : How To Find Solutions To Differential Equations

Solve the differential equation:  \displaystyle \frac{dy}{dx}= \frac{y}{2}

Possible Answers:

\displaystyle y=Ce^x

Correct answer:

Explanation:

Rewrite \displaystyle \frac{dy}{dx}= \frac{y}{2} by multiply the \displaystyle dx on both sides, and dividing \displaystyle y on both sides of the equation.

\displaystyle \frac{1}{y}dy= \frac{1}{2}dx

Integrate both sides of the equation and solve for y.

\displaystyle \int\frac{1}{y}dy= \int\frac{1}{2}dx

\displaystyle ln\left | y\right |=\frac{1}{2}x+C

Learning Tools by Varsity Tutors