Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
3. Writing Equations of Parallel and Perpendicular Lines
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Exercise 12 Page 181

What do parallel lines have in common?

y=3/2x-8

Practice makes perfect

When lines are parallel, they have the same slope. To help us identify the slope of this line, let's first convert it into slope-intercept form, y= mx+ b, where m is the slope and (0, b) is the y-intercept.

2y=3x+10
â–¼
Solve for y
y=3x+10/2
y=3x/2+10/2
y=3/2x+5

With this, we can more easily identify the slope m and y-intercept b.

y= 3/2x+ 5 This means we can write a general equation in slope-intercept form for all lines parallel to the given equation. y= 3/2x+ b We are asked to write the equation of a line parallel to the given equation that passes through the given point ( 2, -5). By substituting this point into the general equation for x and y, we will be able to solve for the y-intercept b of the parallel line.

y=3/2x+b
-5=3/2( 2)+b
â–¼
Solve for b
-5=3+b
-8=b
b=-8

Now that we have the y-intercept, we can write the equation of the line that is parallel to y= 32x+5 and passes through (2,-5). y= 3/2x+( -8) ⇒ y=3/2x-8