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Big Ideas Math Integrated I, 2016

BI

Big Ideas Math Integrated I, 2016 View details

Maintaining Mathematical Proficiency

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Exercise 3 Page 215

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.

4x+5y=20

LHS-4x=RHS-4x

5y=-4x+20

.LHS /5.=.RHS /5.

y = - 4/5 x + 4

Below we highlight the slope m and y-intercept b. y= - 45x+4

The slope is - 45. The y-intercept is 4, so the graph crosses the y-axis at the point (0,4).

Graphing the Equation

A slope of - 45 means that for every 5 units we move in the positive horizontal direction, we move 4 units in the negative vertical direction. m= -4/5 ⇔ rise/run=-4/5 To graph the equation, plot the y-intercept and then use the slope to find another point on the line.

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Exercises p.215