Question

(2a - b)^3

= 8a^3 - 8a^2b + 4ab^2 - b^3

7x^3(2x + 3)

= 14x^4 + 21x^3

Answer 1

(2a-b)^3 = (2a)^3 - 3(2a)^2b + 3(2a)b^2 - b^3

= 8a^3 - 12a^2b + 6ab^2 - b^3
better review your binomial coefficients. I think you used 2 instead of 3.

the other is correct