Lesson 5-5

Writing Equations in Point-Slope Form

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Objectives

• Write the equation in a line in point-slope form

• Write linear equations in different forms

Vocabulary

Point-slope form - an equation of the form y – y1 = m(x – x1), where m is the slope and (x1,y1) is a given point on a nonvertical line

y

x

y

x

x-y Coordinate Plane

Quadrants

III

III IV

Point Plotting

(x, y) (-4, 7) (5, -8)

x – left or righty – up or down

right 5

down 8

left 4

up 7

Example 1

Write the point-slope form of an

equation for a line that passes

through (–2, 0) with slope

Point-slopeform

Simplify.

Answer: The equation is

Example 2

Write the point-slope form of an equation for a horizontal line that passes through (0, 5).

Point-slopeform

Simplify.

Answer: The equation is

Example 3

Write in standard form.

In standard form, the variables are on the left side of the equation. A, B, and C are all integers.

Original equation

Multiply each side by 4 to eliminate the fraction.

Distributive Property

Subtract 3x from each side.

Simplify.

Answer: The standard form of the equation is

Example 4

Write in slope-intercept form.

In slope-intercept form is y = mx + b.

Original equation

Distributive Property

Add 5 to each side.

Simplify and slope intercept form.Answer:

Summary & Homework

• Summary:– The linear equation y – y1 = m(x - x1) is written in

point-slope form, where (x1,y1) is the given point on a nonvertical line and m is the slope

• Homework: – pg 289 16-26, 30-34, 42-48 even