Algebra Examples

y = - 2 x + 10

$y = - 2 x + 10$ through

(10, 7)

$(10, 7)$

Step 1

Use the slope-intercept form to find the slope.

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Step 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 1.2

Using the slope-intercept form, the slope is

- 2

$- 2$ .

m = - 2

$m = - 2$

m = - 2

$m = - 2$

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}{- 2}

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

Step 3

Simplify

- \frac{1}{- 2}

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

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Step 3.1

Move the negative in front of the fraction.

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

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

Step 3.2

Multiply

- - \frac{1}{2}

$- - \frac{1}{2}$ .

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Step 3.2.1

Multiply

- 1

$- 1$ by

- 1

$- 1$ .

m_{perpendicular} = 1 (\frac{1}{2})

$m_{perpendicular} = 1 (\frac{1}{2})$

Step 3.2.2

Multiply

\frac{1}{2}

$\frac{1}{2}$ by

1

$1$ .

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

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

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

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

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

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

Step 4

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

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Step 4.1

Use the slope

\frac{1}{2}

$\frac{1}{2}$ and a given point

(10, 7)

$(10, 7)$ 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) = \frac{1}{2} \cdot (x - (10))

$y - (7) = \frac{1}{2} \cdot (x - (10))$

Step 4.2

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

y - 7 = \frac{1}{2} \cdot (x - 10)

$y - 7 = \frac{1}{2} \cdot (x - 10)$

y - 7 = \frac{1}{2} \cdot (x - 10)

$y - 7 = \frac{1}{2} \cdot (x - 10)$

Step 5

Write in

y = m x + b

$y = m x + b$ form.

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Step 5.1

Solve for

y

$y$ .

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Step 5.1.1

Simplify

\frac{1}{2} \cdot (x - 10)

$\frac{1}{2} \cdot (x - 10)$ .

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Step 5.1.1.1

Rewrite.

y - 7 = 0 + 0 + \frac{1}{2} \cdot (x - 10)

$y - 7 = 0 + 0 + \frac{1}{2} \cdot (x - 10)$

Step 5.1.1.2

Simplify by adding zeros.

y - 7 = \frac{1}{2} \cdot (x - 10)

$y - 7 = \frac{1}{2} \cdot (x - 10)$

Step 5.1.1.3

Apply the distributive property.

y - 7 = \frac{1}{2} x + \frac{1}{2} \cdot - 10

$y - 7 = \frac{1}{2} x + \frac{1}{2} \cdot - 10$

Step 5.1.1.4

Combine

$\frac{1}{2}$ and

$x$ .

$y - 7 = \frac{x}{2} + \frac{1}{2} \cdot - 10$

Step 5.1.1.5

Cancel the common factor of

$2$ .

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Step 5.1.1.5.1

Factor

$2$ out of

$- 10$ .

$y - 7 = \frac{x}{2} + \frac{1}{2} \cdot (2 (- 5))$

Step 5.1.1.5.2

Cancel the common factor.

$y - 7 = \frac{x}{2} + \frac{1}{2} \cdot (2 \cdot - 5)$

Step 5.1.1.5.3

Rewrite the expression.

$y - 7 = \frac{x}{2} - 5$

Step 5.1.2

Move all terms not containing

$y$ to the right side of the equation.

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Step 5.1.2.1

Add

$7$ to both sides of the equation.

$y = \frac{x}{2} - 5 + 7$

Step 5.1.2.2

Add

$- 5$ and

$7$ .

$y = \frac{x}{2} + 2$

Step 5.2

Reorder terms.

$y = \frac{1}{2} x + 2$

Step 6