A line that includes the points (d, – 3) and ( – 10, – 2) has an undefined slope. What is the value of d?

Answer 1

m=(-2-(-3))/(-10-d). And this is undefined whenever its denomerator is zero, that is: -10-d=0. Hence d=-10.

Answer 2

-10

A vertical line has a slope that is undefined and to get a vertical line, the "x" values must be the same.