Hi Mike …can you solve & explain? (from QAS March 2021)

Section 3; #11.

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

The graph in the xy plane of the equation above contains the point (a,b). If -1 < or = a < or = 1, which of the following is NOT a possible value of b?

A) -2

B) -1

C) 0

D) 1

First, just in case this is tripping you up, you can substitute for and for . From there, honestly, I’d just plug in numbers. See what happens when , , and .

When ,

When ,

When ,

Because this is a continuous function, if we know it hits and within that range, it must also go through . So the answer must be D.