Question

What is the slope of a line that passes through the points (4,-2) and (-1,8)

Answer 1

set y = kx+b

for (4,-2): -2=4k+b (function 1)

for (-1,8): 8=-k+b (function 2)

Use function 2 subtract function 1:

10=-5k

k=-2

SO the slope is -2.