Algebra 1 Common Core Student Edition, Grade 8-9

Think about this

situation. The graph

shows th e a ltitu d e

of the balloon with

respect to tim e. I t

doesn't show the

path of the balloon.

. M A T H E M A T I C A L
I P R A C T I C E S

| ' Getting Ready!

•ing it s linear

ep t f o rm? (Hint :

escent at x = 0 ?)

The red line shows t he alt it ude of a I

d escen t. W h at is an eq uat io n o f t h e I

What is the altitude of the balloon w

640

ai

— 600 <D

"O

3 560

640)

(35 580)

(45 560)

@ Common Core State Standards

F-LE.A.2 Co n st r u c t l i n e a r... f u n c t i o n s... g i v en a

graph, a description of a relationship, or two input-

output pairs. A lso A -C E D .A .2 , F-IF.B.4, F-IF.C.7a,

F-LE.B.5

M P 1, M P 3, M P 4

Objective To write an d g raph lin ear eq u atio n s using point-slope form

Point-Slope Form

20

Ti me

^ Lesson t
Vocabulary
point-slope form

You have learn ed how to w rite an eq u a tio n of a line by using its y-intercept. In this

lesson, you will learn how to w rite a n eq u a tio n without u s i n g t h e y - i n t e r c e p t.

Esse n t i a l U n d e r st a n d i n g You can use the slope of a line and any point on the line to

write and graph an equation of the line. Any two equations for the sam e line are equivalent.

Key Concep t Point-Slope Form of a Linear Equation

Definition Graph

The point-slope form of an equation of a

nonvertical line w ith slope m a n d through

point [xv y x) is y - y1 = m (x - x x).

Symbols

y - y x = m[x - Xj)

t f t

y-coordinate slope x-coordinate

y m _ riseru n /

y

V (*i\y)

X

0

When you use

y - y, = m(x - x,),

(xv y.|) represents

a specific point and

(x, y) represents

any point.

If PowerAlgebra.com ....j h; 3,1 5

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