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Find the equation of a line parallel to y + 9 = -3/2x that passes through the point (-8,9)

Find the equation of a line parallel to y + 9 = -3/2x that passes through the point-example-1

1 Answer

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Parallel lines have equal slope but different y-intercepts.

slope intercept form:
y = mx + b (where m = slope
and b = y-intercept)

simply subtract 9 from both sides of the given equation to get slope intercept form of the first line:
y + 9 = -3/2x
y + 9 - 9 = -3/2x - 9
y = -3/2x - 9

so the slope (m) = -3/2

the problem tells us a point on the second line (x,y) or (-8,9)

and we now know slope is -3/2

so let’s plug those in and solve for the y-intercept (b) of the second line.

y = mx + b
9 = -3/2(-8) + b
9 = 12 + b
9 - 12 = 12 - 12 + b
-3 = b

so now we know the slope (m) of both lines is -3/2 and the y-intercept (b) of the second line is -3

all we have to do is use the information to establish slope intercept form of the equation of the second line:

y = mx + b
y = -3/2x - 3

The answer is: y = -3/2x - 3

check your answer by plugging the point (-8,9) back in to your equation

9 = -3/2(-8) - 3
9 = 12 - 3
9 = 9 [TRUE]
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