Question

9x^4 - 148x^2 + 64

Answer 1

Consider the quadratic:

9z^2 - 148z + 64

Its roots are:
(148 ±√(21904-2304))/18
= (148±140)/18
.: either 4/9 or 16

Thus we can factorise the quartic:
9x^4 - 148x^2 + 64
= (9x^2 - 4)(x^2 - 16)

Next, factorise each of these two quadratic terms in turn.