Algebra Examples

(8, - 7)

$(8, - 7)$

y = \frac{x}{2} - 9

$y = \frac{x}{2} - 9$

Step 1

Find the slope when

y = \frac{x}{2} - 9

$y = \frac{x}{2} - 9$ .

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Step 1.1

Rewrite in slope-intercept form.

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Step 1.1.1

The slope-intercept form is

y = m x + b

$y = m x + b$ , where

m

$m$ is the slope and

b

$b$ is the y-intercept.

y = m x + b

$y = m x + b$

Step 1.1.2

Reorder terms.

y = \frac{1}{2} x - 9

$y = \frac{1}{2} x - 9$

y = \frac{1}{2} x - 9

$y = \frac{1}{2} x - 9$

Step 1.2

Using the slope-intercept form, the slope is

\frac{1}{2}

$\frac{1}{2}$ .

m = \frac{1}{2}

$m = \frac{1}{2}$

m = \frac{1}{2}

$m = \frac{1}{2}$

Step 2

The equation of a perpendicular line must have a slope that is the negative reciprocal of the original slope.

m_{perpendicular} = - \frac{1}{\frac{1}{2}}

$m_{perpendicular} = - \frac{1}{\frac{1}{2}}$

Step 3

Simplify

- \frac{1}{\frac{1}{2}}

$- \frac{1}{\frac{1}{2}}$ to find the slope of the perpendicular line.

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Step 3.1

Multiply the numerator by the reciprocal of the denominator.

m_{perpendicular} = - (1 \cdot 2)

$m_{perpendicular} = - (1 \cdot 2)$

Step 3.2

Multiply

- (1 \cdot 2)

$- (1 \cdot 2)$ .

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Step 3.2.1

Multiply

2

$2$ by

1

$1$ .

m_{perpendicular} = - 1 \cdot 2

$m_{perpendicular} = - 1 \cdot 2$

Step 3.2.2

Multiply

- 1

$- 1$ by

2

$2$ .

m_{perpendicular} = - 2

$m_{perpendicular} = - 2$

m_{perpendicular} = - 2

$m_{perpendicular} = - 2$

m_{perpendicular} = - 2

$m_{perpendicular} = - 2$

Step 4

Find the equation of the perpendicular line using the point-slope formula.

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Step 4.1

Use the slope

- 2

$- 2$ and a given point

(8, - 7)

$(8, - 7)$ to substitute for

x_{1}

$x_{1}$ and

y_{1}

$y_{1}$ in the point-slope form

y - y_{1} = m (x - x_{1})

$y - y_{1} = m (x - x_{1})$ , which is derived from the slope equation

m = \frac{y_{2} - y_{1}}{x_{2} - x_{1}}

$m = \frac{y_{2} - y_{1}}{x_{2} - x_{1}}$ .

y - (- 7) = - 2 \cdot (x - (8))

$y - (- 7) = - 2 \cdot (x - (8))$

Step 4.2

Simplify the equation and keep it in point-slope form.

y + 7 = - 2 \cdot (x - 8)

$y + 7 = - 2 \cdot (x - 8)$

y + 7 = - 2 \cdot (x - 8)

$y + 7 = - 2 \cdot (x - 8)$

Step 5

Solve for

y

$y$ .

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Step 5.1

Simplify

- 2 \cdot (x - 8)

$- 2 \cdot (x - 8)$ .

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Step 5.1.1

Rewrite.

y + 7 = 0 + 0 - 2 \cdot (x - 8)

$y + 7 = 0 + 0 - 2 \cdot (x - 8)$

Step 5.1.2

Simplify by adding zeros.

y + 7 = - 2 \cdot (x - 8)

$y + 7 = - 2 \cdot (x - 8)$

Step 5.1.3

Apply the distributive property.

y + 7 = - 2 x - 2 \cdot - 8

$y + 7 = - 2 x - 2 \cdot - 8$

Step 5.1.4

Multiply

- 2

$- 2$ by

- 8

$- 8$ .

y + 7 = - 2 x + 16

$y + 7 = - 2 x + 16$

y + 7 = - 2 x + 16

$y + 7 = - 2 x + 16$

Step 5.2

Move all terms not containing

y

$y$ to the right side of the equation.

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Step 5.2.1

Subtract

7

$7$ from both sides of the equation.

y = - 2 x + 16 - 7

$y = - 2 x + 16 - 7$

Step 5.2.2

Subtract

7

$7$ from

16

$16$ .

y = - 2 x + 9

$y = - 2 x + 9$

y = - 2 x + 9

$y = - 2 x + 9$

y = - 2 x + 9

$y = - 2 x + 9$

Step 6