Question

Làm tính nhân:

\(\text{ (2a – b)(4a^2 + 2ab + b^2)}\)

Answer 1

\(\text{(2a – b)(4a^2 + 2ab +b^2)}\)

= \(\text{2a.4a^2 + 2a.2ab + 2a.b^2 + (-b).4a^2 + (-b).2ab + (-b).b^2}\)

= \(\text{8a^3 + 4a^2b + 2ab^2 – 4a^2b – 2ab^2 – b^3 = 8a^3 – b^3}\)

Answer 2

2a – b)(4a^2 + 2ab +b^2)

= 2a.4a^2 + 2a.2ab + 2a.b^2 + (-b).4a^2 + (-b).2ab + (-b).b^2

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

= 8a^3 – b^3

\(2a – b)(4a^2 + 2ab +b^2) = 2a.4a^2 + 2a.2ab + 2a.b^2 + (-b).4a^2 + (-b).2ab + (-b).b^2 = 8a^3 + 4a^2b + 2ab^2 – 4a^2b – 2ab^2 – b^3 = 8a^3 – b^3\)