list potential rational zeros

Question

f(x)=x^4+3x^2-4

Answer 1

let z = x^2
then
z^2 + 3 z - 4 = 0
(z-4)(z+1) = 0
z = 4 or z = 1
so
x^2 = 4 or x^2 = 1
so
+/- 2 and +/- 1