Find the common factors of the given term.
16, -4, 32x
∵ 16 = 2 × 2 × 2 × 2 × x × x × x = (2 × 2 × x) × 2 × 2 × x × x
-4 = -1 × 2 × 2 × x × x = (2 × 2 × x) × (-1) × x
32x = 2 × 2 × 2 × 2 × 2 × x = (2 × 2 × x) × 2 × 2 × 2
∴ the common factor = 2 × 2 × x = 4x