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Pearson Algebra 2 Common Core, 2011 View details

3. Linear Functions and Slope-Intercept Form

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Exercise 45 Page 79

What information does a slope-intercept form equation give you?

Practice makes perfect

Equations written in slope-intercept form follow a specific format. y=mx+ b In this form, m represents the slope of the line and b represents the y-intercept.

Identifying Slope and Intercept

Since the given equation is not in slope-intercept form, let's rewrite it so that it will be easier to identify the slope and y-intercept.

2.4=-3.6x-0.4y

AddEqn

LHS+0.4y=RHS+0.4y

2.4+0.4y=-3.6x

SubEqn

LHS-2.4=RHS-2.4

0.4y=-3.6x-2.4

DivEqn

.LHS /0.4.=.RHS /0.4.

y=-9x-6

Below we highlight the slope m and y-intercept b. y=-9x - 6 ⇔ y=-9x+( -6) The slope is -9. The y-intercept is -6, so the graph crosses the y-axis at the point (0, -6).

Graphing the Equation

A slope of -9 means that for every 1 unit we move in the positive horizontal direction, we move 9 units in the negative vertical direction. m=-9/1 ⇔ rise/run=-9/1 To graph the equation, plot the y-intercept and then use the slope to find another point on the line.

Subchapter links

Lesson Check p.78

Practice and Problem-Solving Exercises p.78-80

Standardized Test Prep p.80

Mixed Review p.80

Exercise 45 Page 79

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Practice exercises

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Identifying Slope and Intercept

Graphing the Equation