Answer:
(2x - 1)(2x + 1)(x - 7)
Step-by-step explanation:
We use grouping to factor.
Step 1: Group 1st 2 terms together and factor
4x³ - 28x²
4x²(x - 7)
Step 2: Group last 2 terms together and factor
-x + 7
-1(x - 7)
Step 3: Combine
(4x² - 1)(x - 7)
Step 4: Factor out quadratic
(2x - 1)(2x + 1)(x - 7)
