9. If f is a linear function such that f(-1) = 5 and f(2) = -1, then f(x + 1) =

Question

A. -2x + 1
B. -2x + 3
C. x + 1
D. -2x + 2
E. 2x + 1

Answer 1

use the two-point form of a line and you can see that

(y-5)/(x+1) = (5+1)/(-1-2)
y-5 = -2(x+1)
y = -2(x+1)+5

So,
y(x+1) = -2((x+1)+1)+5
= -2(x+2)+5
= -2x-4+5
= -2x+1