Big Ideas Math Integrated I, 2016
BI
Big Ideas Math Integrated I, 2016 View details
3. Writing Equations of Parallel and Perpendicular Lines
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Exercise 10 Page 181

What do parallel lines have in common?

y=-5x+7

Practice makes perfect

When lines are parallel, they have the same slope. y= -5x+ 4 In the given equation, we can see that the line has a slope of -5. Therefore we know that all lines that are parallel to our given line will have a slope of -5. This means we can write a general equation in slope-intercept form for all lines parallel to the given equation. y=-5x+ b We are asked to write the equation of a line parallel to the given equation that passes through the given point ( 1, 2). 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=-5x+b
2=-5( 1)+b
â–¼
Solve for b
2=-5+b
7=b
b=7

Now that we have the y-intercept, we can write the equation for the line that is parallel to y=-5x+4 and passes through the point (1,2). y= -5x+ 7