Question

A line with a slope of 3 passes through the points (-3, 4) and (a, -8). What is the value of a?

Answer 1

using the slope formula:

m = y2-y1/x2-x1

3 = -8 - 4/a- -3

3 = -12/a+3

multiply each side by a +3

3a + 9 = -12

move the 9 over by subtraction

3a = -21

divide by 3

a = -7

check it:

3 = -8 - 4/-7 - -3

3 = -12/-4

3 = 3