а) 42 = 2 × 3 × 7
б) 72 = 2 × 2 × 2 × 3 × 3 = $$2^3 \cdot 3^2$$
в) 128 = 2 × 2 × 2 × 2 × 2 × 2 × 2 = $$2^7$$
г) 275 = 5 × 5 × 11 = $$5^2 \cdot 11$$