Question

[Quoc Tran Anh Le]

Tính:

a) \(\dfrac{1}{2}x(6x - 4)\);

b) \( - {x^2}(\dfrac{1}{3}{x^2} - x - \dfrac{1}{4})\).

Answer 1

[Hà Quang Minh]

a) \(\dfrac{1}{2}x(6x - 4) = \dfrac{1}{2}x.6x + \dfrac{1}{2}x.( - 4) = 3{x^2} - 2x\).

b) \(\begin{array}{l} - {x^2}(\dfrac{1}{3}{x^2} - x - \dfrac{1}{4}) =  - {x^2}.\dfrac{1}{3}{x^2} +  - {x^2}. - x +  - {x^2}. - \dfrac{1}{4}\\ =  - \dfrac{1}{3}{x^4} + {x^3} + \dfrac{1}{4}{x^2}\end{array}\)