Precalculus Examples

$\frac{y^{2}}{4} - \frac{x^{2}}{49} = 1$

Step 1

Add $\frac{x^{2}}{49}$ to both sides of the equation.

$\frac{y^{2}}{4} = 1 + \frac{x^{2}}{49}$

Step 2

Multiply both sides of the equation by $4$ .

$4 \frac{y^{2}}{4} = 4 (1 + \frac{x^{2}}{49})$

Step 3

Simplify both sides of the equation.

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Step 3.1

Simplify the left side.

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Step 3.1.1

Cancel the common factor of $4$ .

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Step 3.1.1.1

Cancel the common factor.

$4 \frac{y^{2}}{4} = 4 (1 + \frac{x^{2}}{49})$

Step 3.1.1.2

Rewrite the expression.

$y^{2} = 4 (1 + \frac{x^{2}}{49})$

Step 3.2

Simplify the right side.

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Step 3.2.1

Simplify $4 (1 + \frac{x^{2}}{49})$ .

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Step 3.2.1.1

Apply the distributive property.

$y^{2} = 4 \cdot 1 + 4 \frac{x^{2}}{49}$

Step 3.2.1.2

Multiply $4$ by $1$ .

$y^{2} = 4 + 4 \frac{x^{2}}{49}$

Step 3.2.1.3

Combine $4$ and $\frac{x^{2}}{49}$ .

$y^{2} = 4 + \frac{4 x^{2}}{49}$

Step 4

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

$y = \pm \sqrt{4 + \frac{4 x^{2}}{49}}$

Step 5

Simplify $\pm \sqrt{4 + \frac{4 x^{2}}{49}}$ .

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Step 5.1

To write $4$ as a fraction with a common denominator, multiply by $\frac{49}{49}$ .

$y = \pm \sqrt{4 \cdot \frac{49}{49} + \frac{4 x^{2}}{49}}$

Step 5.2

Combine $4$ and $\frac{49}{49}$ .

$y = \pm \sqrt{\frac{4 \cdot 49}{49} + \frac{4 x^{2}}{49}}$

Step 5.3

Combine the numerators over the common denominator.

$y = \pm \sqrt{\frac{4 \cdot 49 + 4 x^{2}}{49}}$

Step 5.4

Factor $4$ out of $4 \cdot 49 + 4 x^{2}$ .

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Step 5.4.1

Factor $4$ out of $4 \cdot 49$ .

$y = \pm \sqrt{\frac{4 (49) + 4 x^{2}}{49}}$

Step 5.4.2

Factor $4$ out of $4 x^{2}$ .

$y = \pm \sqrt{\frac{4 (49) + 4 (x^{2})}{49}}$

Step 5.4.3

Factor $4$ out of $4 (49) + 4 (x^{2})$ .

$y = \pm \sqrt{\frac{4 (49 + x^{2})}{49}}$

Step 5.5

Rewrite $\frac{4 (49 + x^{2})}{49}$ as ${(\frac{2}{7})}^{2} (7^{2} + x^{2})$ .

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Step 5.5.1

Factor the perfect power $2^{2}$ out of $4 (49 + x^{2})$ .

$y = \pm \sqrt{\frac{2^{2} (7^{2} + x^{2})}{49}}$

Step 5.5.2

Factor the perfect power $7^{2}$ out of $49$ .

$y = \pm \sqrt{\frac{2^{2} (7^{2} + x^{2})}{7^{2} \cdot 1}}$

Step 5.5.3

Rearrange the fraction $\frac{2^{2} (7^{2} + x^{2})}{7^{2} \cdot 1}$ .

$y = \pm \sqrt{{(\frac{2}{7})}^{2} (7^{2} + x^{2})}$

Step 5.6

Pull terms out from under the radical.

$y = \pm \frac{2}{7} \sqrt{7^{2} + x^{2}}$

Step 5.7

Raise $7$ to the power of $2$ .

$y = \pm \frac{2}{7} \sqrt{49 + x^{2}}$

Step 5.8

Combine $\frac{2}{7}$ and $\sqrt{49 + x^{2}}$ .

$y = \pm \frac{2 \sqrt{49 + x^{2}}}{7}$

Step 6

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

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Step 6.1

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

$y = \frac{2 \sqrt{49 + x^{2}}}{7}$

Step 6.2

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

$y = - \frac{2 \sqrt{49 + x^{2}}}{7}$

Step 6.3

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

$y = \frac{2 \sqrt{49 + x^{2}}}{7}$

$y = - \frac{2 \sqrt{49 + x^{2}}}{7}$

$y = \frac{2 \sqrt{49 + x^{2}}}{7}$

$y = - \frac{2 \sqrt{49 + x^{2}}}{7}$

Step 7

Set the radicand in $\sqrt{49 + x^{2}}$ greater than or equal to $0$ to find where the expression is defined.

$49 + x^{2} \geq 0$

Step 8

Solve for $x$ .

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Step 8.1

Subtract $49$ from both sides of the inequality.

$x^{2} \geq - 49$

Step 8.2

Since the left side has an even power, it is always positive for all real numbers.

All real numbers

Step 9

The domain is all real numbers.

Interval Notation:

$(- \infty, \infty)$

Set-Builder Notation:

${x | x \in ℝ}$

Step 10

The range is the set of all valid $y$ values. Use the graph to find the range.

Interval Notation:

$(- \infty, - 2] \cup [2, \infty)$

Set-Builder Notation:

${y | y \leq - 2, y \geq 2}$

Step 11

Determine the domain and range.

Domain: $(- \infty, \infty), {x | x \in ℝ}$

Range: $(- \infty, - 2] \cup [2, \infty), {y | y \leq - 2, y \geq 2}$

Step 12