Question

If (a+1)(2-a) < 0
(a) -2 < a <1
(b) a< -2 or a > 1
(c) a < -2 or a < 1
(d) -1 < a < 2
(e) a > 2 or a < -1

Answer 1

\[y=(a+1)(2-a)\] is a parabola that opens down (we know this because if you multiply out you will get a term \(-a^2\) therefore it looks like this

Answer 2

the zeros are at \(a=-1\) and \(a=2\) and as you can see it is negative (below the axis) outside the zeros and positive between them

Answer 3

@satellite73 would the answer choice be (d) or (e) then?