Page 138 - Math Course 3 (Book 1)

Equations with Slope and Points on the Line
Mo. 4

Lesson 4 Therefore, the equation is y = 0.357x + 2.148

y = 0.357x + 2.148 Original equation
= 0.357(72) + 2.148 Replace x with 72
KEY CONCEPTS: ≈ 28 Simplify
1. Write an equation of a line given the slope
and one point on a line.
2. Write an equation of a line given two points Let’s Begin
on the line.
3. Write an equation of a line given two points
on the line to solve problems.
Write an Equation Given Slope and One Point

MO. 4 - L4a Example

Equations Using
Slope-Intercept Form Write an equation of a line that passes through
(2, –3) with slope 1
2
Vocabulary A-Z Step 1 Find the y-intercept by replacing m with 1
2
Let us learn some vocabulary and (x, y) with (2, –3) in the slope-intercept
form and solving for b.

y = mx + b Slope-intercept form
linear extrapolation 1
1
When you use a linear equation to predict values –3 = (2) + b Replace m with y with –3
2
that are beyond the range of the data, you are 2 and x with 2.
using linear extrapolation.
–3 = 1 + b Multiply.
y
30 –3 – 1= 1 + b – 1 Subtract 1 from each side.
Members of RBI 20 (22,10) Step 2 Write the slope-intercept form using
25
(26,15)
Simplify.
–4 = b
15
10
1
5
2
10 20 30 40 x m = and b = –4
Games y = mx + b Slope-intercept form
Choose (36, 15) and find the y-intercept of the line.
1
1
y = x –4 Replace m with and b
y = mx + b Slope-intercept form 2 with –4. 2
15 = 0.357(36) + b Replace m with 0.357, x with
1
36 and, y with 15 Answer The equation is y = x –4
2
15 = 12.852 + b Multiply
Check You can check your result by graphing
2.148 = b 1
on a graphing calculator.
y = x –4
2
Write the slope-intercept from using m = 0.357, and
b = 2.148

y = mx + b Slope-intercept form
y = 0.35yx + 2.148 Replace m with 0.357, and b
with 2.148. Use the CALC menu to verify.

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