Calculus Examples

$4 x^{2} + 5 y \frac{d y}{d x} = 0$

Step 1

Separate the variables.

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Step 1.1

Solve for $\frac{d y}{d x}$ .

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Step 1.1.1

Subtract $4 x^{2}$ from both sides of the equation.

$5 y \frac{d y}{d x} = - 4 x^{2}$

Step 1.1.2

Divide each term in $5 y \frac{d y}{d x} = - 4 x^{2}$ by $5 y$ and simplify.

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Step 1.1.2.1

Divide each term in $5 y \frac{d y}{d x} = - 4 x^{2}$ by $5 y$ .

$\frac{5 y \frac{d y}{d x}}{5 y} = \frac{- 4 x^{2}}{5 y}$

Step 1.1.2.2

Simplify the left side.

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Step 1.1.2.2.1

Cancel the common factor of $5$ .

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Step 1.1.2.2.1.1

Cancel the common factor.

$\frac{5 y \frac{d y}{d x}}{5 y} = \frac{- 4 x^{2}}{5 y}$

Step 1.1.2.2.1.2

Rewrite the expression.

$\frac{y \frac{d y}{d x}}{y} = \frac{- 4 x^{2}}{5 y}$

Step 1.1.2.2.2

Cancel the common factor of $y$ .

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Step 1.1.2.2.2.1

Cancel the common factor.

$\frac{y \frac{d y}{d x}}{y} = \frac{- 4 x^{2}}{5 y}$

Step 1.1.2.2.2.2

Divide $\frac{d y}{d x}$ by $1$ .

$\frac{d y}{d x} = \frac{- 4 x^{2}}{5 y}$

Step 1.1.2.3

Simplify the right side.

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Step 1.1.2.3.1

Move the negative in front of the fraction.

$\frac{d y}{d x} = - \frac{4 x^{2}}{5 y}$

Step 1.2

Multiply both sides by $y$ .

$y \frac{d y}{d x} = y (- \frac{4 x^{2}}{5 y})$

Step 1.3

Simplify.

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Step 1.3.1

Rewrite using the commutative property of multiplication.

$y \frac{d y}{d x} = - y \frac{4 x^{2}}{5 y}$

Step 1.3.2

Cancel the common factor of $y$ .

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Step 1.3.2.1

Factor $y$ out of $- y$ .

$y \frac{d y}{d x} = y \cdot - 1 \frac{4 x^{2}}{5 y}$

Step 1.3.2.2

Factor $y$ out of $5 y$ .

$y \frac{d y}{d x} = y \cdot - 1 \frac{4 x^{2}}{y \cdot 5}$

Step 1.3.2.3

Cancel the common factor.

$y \frac{d y}{d x} = y \cdot - 1 \frac{4 x^{2}}{y \cdot 5}$

Step 1.3.2.4

Rewrite the expression.

$y \frac{d y}{d x} = - \frac{4 x^{2}}{5}$

Step 1.4

Rewrite the equation.

$y d y = - \frac{4 x^{2}}{5} d x$

Step 2

Integrate both sides.

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Step 2.1

Set up an integral on each side.

$\int y d y = \int - \frac{4 x^{2}}{5} d x$

Step 2.2

By the Power Rule, the integral of $y$ with respect to $y$ is $\frac{1}{2} y^{2}$ .

$\frac{1}{2} y^{2} + C_{1} = \int - \frac{4 x^{2}}{5} d x$

Step 2.3

Integrate the right side.

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Step 2.3.1

Since $- 1$ is constant with respect to $x$ , move $- 1$ out of the integral.

$\frac{1}{2} y^{2} + C_{1} = - \int \frac{4 x^{2}}{5} d x$

Step 2.3.2

Since $\frac{4}{5}$ is constant with respect to $x$ , move $\frac{4}{5}$ out of the integral.

$\frac{1}{2} y^{2} + C_{1} = - (\frac{4}{5} \int x^{2} d x)$

Step 2.3.3

By the Power Rule, the integral of $x^{2}$ with respect to $x$ is $\frac{1}{3} x^{3}$ .

$\frac{1}{2} y^{2} + C_{1} = - \frac{4}{5} (\frac{1}{3} x^{3} + C_{2})$

Step 2.3.4

Simplify the answer.

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Step 2.3.4.1

Rewrite $- \frac{4}{5} (\frac{1}{3} x^{3} + C_{2})$ as $- \frac{4}{5} \cdot \frac{1}{3} x^{3} + C_{2}$ .

$\frac{1}{2} y^{2} + C_{1} = - \frac{4}{5} \cdot \frac{1}{3} x^{3} + C_{2}$

Step 2.3.4.2

Simplify.

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Step 2.3.4.2.1

Multiply $\frac{1}{3}$ by $\frac{4}{5}$ .

$\frac{1}{2} y^{2} + C_{1} = - \frac{4}{3 \cdot 5} x^{3} + C_{2}$

Step 2.3.4.2.2

Multiply $3$ by $5$ .

$\frac{1}{2} y^{2} + C_{1} = - \frac{4}{15} x^{3} + C_{2}$

Step 2.4

Group the constant of integration on the right side as $K$ .

$\frac{1}{2} y^{2} = - \frac{4}{15} x^{3} + K$

Step 3

Solve for $y$ .

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Step 3.1

Multiply both sides of the equation by $2$ .

$2 (\frac{1}{2} y^{2}) = 2 (- \frac{4}{15} x^{3} + K)$

Step 3.2

Simplify both sides of the equation.

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Step 3.2.1

Simplify the left side.

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Step 3.2.1.1

Simplify $2 (\frac{1}{2} y^{2})$ .

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Step 3.2.1.1.1

Combine $\frac{1}{2}$ and $y^{2}$ .

$2 \frac{y^{2}}{2} = 2 (- \frac{4}{15} x^{3} + K)$

Step 3.2.1.1.2

Cancel the common factor of $2$ .

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Step 3.2.1.1.2.1

Cancel the common factor.

$2 \frac{y^{2}}{2} = 2 (- \frac{4}{15} x^{3} + K)$

Step 3.2.1.1.2.2

Rewrite the expression.

$y^{2} = 2 (- \frac{4}{15} x^{3} + K)$

Step 3.2.2

Simplify the right side.

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Step 3.2.2.1

Simplify $2 (- \frac{4}{15} x^{3} + K)$ .

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Step 3.2.2.1.1

Simplify each term.

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Step 3.2.2.1.1.1

Combine $x^{3}$ and $\frac{4}{15}$ .

$y^{2} = 2 (- \frac{x^{3} \cdot 4}{15} + K)$

Step 3.2.2.1.1.2

Move $4$ to the left of $x^{3}$ .

$y^{2} = 2 (- \frac{4 x^{3}}{15} + K)$

Step 3.2.2.1.2

Apply the distributive property.

$y^{2} = 2 (- \frac{4 x^{3}}{15}) + 2 K$

Step 3.2.2.1.3

Multiply $2 (- \frac{4 x^{3}}{15})$ .

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Step 3.2.2.1.3.1

Multiply $- 1$ by $2$ .

$y^{2} = - 2 \frac{4 x^{3}}{15} + 2 K$

Step 3.2.2.1.3.2

Combine $- 2$ and $\frac{4 x^{3}}{15}$ .

$y^{2} = \frac{- 2 (4 x^{3})}{15} + 2 K$

Step 3.2.2.1.3.3

Multiply $4$ by $- 2$ .

$y^{2} = \frac{- 8 x^{3}}{15} + 2 K$

Step 3.2.2.1.4

Move the negative in front of the fraction.

$y^{2} = - \frac{8 x^{3}}{15} + 2 K$

Step 3.3

Take the specified root of both sides of the equation to eliminate the exponent on the left side.

$y = \pm \sqrt{- \frac{8 x^{3}}{15} + 2 K}$

Step 3.4

Simplify $\pm \sqrt{- \frac{8 x^{3}}{15} + 2 K}$ .

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Step 3.4.1

Factor $2$ out of $- \frac{8 x^{3}}{15} + 2 K$ .

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Step 3.4.1.1

Factor $2$ out of $- \frac{8 x^{3}}{15}$ .

$y = \pm \sqrt{2 (- \frac{4 x^{3}}{15}) + 2 K}$

Step 3.4.1.2

Factor $2$ out of $2 K$ .

$y = \pm \sqrt{2 (- \frac{4 x^{3}}{15}) + 2 K}$

Step 3.4.1.3

Factor $2$ out of $2 (- \frac{4 x^{3}}{15}) + 2 K$ .

$y = \pm \sqrt{2 (- \frac{4 x^{3}}{15} + K)}$

Step 3.4.2

To write $K$ as a fraction with a common denominator, multiply by $\frac{15}{15}$ .

$y = \pm \sqrt{2 (- \frac{4 x^{3}}{15} + K \cdot \frac{15}{15})}$

Step 3.4.3

Simplify terms.

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Step 3.4.3.1

Combine $K$ and $\frac{15}{15}$ .

$y = \pm \sqrt{2 (- \frac{4 x^{3}}{15} + \frac{K \cdot 15}{15})}$

Step 3.4.3.2

Combine the numerators over the common denominator.

$y = \pm \sqrt{2 \frac{- 4 x^{3} + K \cdot 15}{15}}$

Step 3.4.4

Move $15$ to the left of $K$ .

$y = \pm \sqrt{2 \frac{- 4 x^{3} + 15 K}{15}}$

Step 3.4.5

Combine $2$ and $\frac{- 4 x^{3} + 15 K}{15}$ .

$y = \pm \sqrt{\frac{2 (- 4 x^{3} + 15 K)}{15}}$

Step 3.4.6

Rewrite $\sqrt{\frac{2 (- 4 x^{3} + 15 K)}{15}}$ as $\frac{\sqrt{2 (- 4 x^{3} + 15 K)}}{\sqrt{15}}$ .

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)}}{\sqrt{15}}$

Step 3.4.7

Multiply $\frac{\sqrt{2 (- 4 x^{3} + 15 K)}}{\sqrt{15}}$ by $\frac{\sqrt{15}}{\sqrt{15}}$ .

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)}}{\sqrt{15}} \cdot \frac{\sqrt{15}}{\sqrt{15}}$

Step 3.4.8

Combine and simplify the denominator.

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Step 3.4.8.1

Multiply $\frac{\sqrt{2 (- 4 x^{3} + 15 K)}}{\sqrt{15}}$ by $\frac{\sqrt{15}}{\sqrt{15}}$ .

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{\sqrt{15} \sqrt{15}}$

Step 3.4.8.2

Raise $\sqrt{15}$ to the power of $1$ .

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{{\sqrt{15}}^{1} \sqrt{15}}$

Step 3.4.8.3

Raise $\sqrt{15}$ to the power of $1$ .

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{{\sqrt{15}}^{1} {\sqrt{15}}^{1}}$

Step 3.4.8.4

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{{\sqrt{15}}^{1 + 1}}$

Step 3.4.8.5

Add $1$ and $1$ .

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{{\sqrt{15}}^{2}}$

Step 3.4.8.6

Rewrite ${\sqrt{15}}^{2}$ as $15$ .

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Step 3.4.8.6.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{15}$ as $15^{\frac{1}{2}}$ .

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{{(15^{\frac{1}{2}})}^{2}}$

Step 3.4.8.6.2

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{15^{\frac{1}{2} \cdot 2}}$

Step 3.4.8.6.3

Combine $\frac{1}{2}$ and $2$ .

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{15^{\frac{2}{2}}}$

Step 3.4.8.6.4

Cancel the common factor of $2$ .

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Step 3.4.8.6.4.1

Cancel the common factor.

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{15^{\frac{2}{2}}}$

Step 3.4.8.6.4.2

Rewrite the expression.

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{15^{1}}$

Step 3.4.8.6.5

Evaluate the exponent.

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K)} \sqrt{15}}{15}$

Step 3.4.9

Simplify the numerator.

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Step 3.4.9.1

Combine using the product rule for radicals.

$y = \pm \frac{\sqrt{2 (- 4 x^{3} + 15 K) \cdot 15}}{15}$

Step 3.4.9.2

Multiply $15$ by $2$ .

$y = \pm \frac{\sqrt{30 (- 4 x^{3} + 15 K)}}{15}$

Step 3.5

The complete solution is the result of both the positive and negative portions of the solution.

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Step 3.5.1

First, use the positive value of the $\pm$ to find the first solution.

$y = \frac{\sqrt{30 (- 4 x^{3} + 15 K)}}{15}$

Step 3.5.2

Next, use the negative value of the $\pm$ to find the second solution.

$y = - \frac{\sqrt{30 (- 4 x^{3} + 15 K)}}{15}$

Step 3.5.3

The complete solution is the result of both the positive and negative portions of the solution.

$y = \frac{\sqrt{30 (- 4 x^{3} + 15 K)}}{15}$

$y = - \frac{\sqrt{30 (- 4 x^{3} + 15 K)}}{15}$

$y = \frac{\sqrt{30 (- 4 x^{3} + 15 K)}}{15}$

$y = - \frac{\sqrt{30 (- 4 x^{3} + 15 K)}}{15}$

$y = \frac{\sqrt{30 (- 4 x^{3} + 15 K)}}{15}$

$y = - \frac{\sqrt{30 (- 4 x^{3} + 15 K)}}{15}$

Step 4

Simplify the constant of integration.

$y = \frac{\sqrt{30 (- 4 x^{3} + K)}}{15}$

$y = - \frac{\sqrt{30 (- 4 x^{3} + K)}}{15}$