Answer:
(x² - 7)(x² - 4)
Explanation:
We can actually factor this the same way we would solve a normal quadratic equation. We will end up with the factored terms have squares of x instead of just x.
x⁴ - 11x² + 28
= x⁴ - 4x² - 7x² + 28
= x²(x² - 4) - 7(x² - 4)
= (x² - 7)(x² - 4)