Warm – up #2

1. Does y vary directly with x ? If so, what is the constant of variation, and the function rule?

2. y varies directly withx, and y = 24 when x = -15, what is x when y = 16

Warm – up #2 Solutions

1. .5

Yes, y varies directly with x.

The constant of variation k is 2.5

y = kx y = 2.5x

Warm – up #2 Solutions

2. Suppose y varies directly with x, and y = 24, when x = -15. What is x when y = 16.

24x = -15(16) 24x = -240 24 24

x =-10

Lesson 2-3 Linear Functions & Slope-Intercept FormAlgebra II

Learning Objective

To write equations of lines in slope-intercept form

Linear Equation – represents a linear function.

y = 3x – 7

Solution of a linear equation – any ordered pair (x, y) that makes the equation true.

Slope-intercept form – an equation of a line

y = mx + b y-intercept

slope

y-intercept – point where line crosses y-axis

x-intercept – point where line crosses x-axis

Writing Linear Equations

1. m= and y-intercept is (0, -3)

2. m = 6 and y-intercept is (0, 5)

To rewrite a linear equation into slope-intercept form

Get the equation into y=𝑚𝑥+𝑏 by solving for y.

Write equation in slope-intercept form. What are the slope & y-intercept?

3. 5x – 4y = 16 -5x -5x

-4y = -5x + 16-4 -4 -4y =

Slope = y-int: (0, -4)

Write equation in slope-intercept form. What are the slope & y-intercept?

4. 3x + 2y = 18 -3x -3x

2y = -3x + 18 2 2 2y =

Slope = y-int: (0, 9)

Write equation in slope-intercept form. What are the slope & y-intercept?

5.

(4)(4)

-3x + 2y = -4+3x +3x2y = 3x – 42 2 2y =

Slope = y-int: (0, -2)

Find Slope

6. Line 1: (2, 4) & (4, 2)

Line 2: (-1, -3) & (3, 1)

Are the lines parallel, perpendicular, or neither? Why?

They are perpendicular

because the slopes 1 and -1 are opposite

reciprocals!

Ticket Out the Door

y=12 + 10x models the amount of money in your wallet.

y = total in dollarsx = # of weeks from today

1. Is it in slope intercept form?2. What is the slope?3. What does the slope represent?

Assignment:

Pg. 78 # 13 – 27 odd, 47 – 49, CC *7, *46, *58