Rút gọn các biểu thức: 3x(x – 2) – 5x(1 – x) – 8(x^2 – 3)
Giải thích
3x(x – 2) – 5x(1 – x) – 8(x2 – 3)
= 3x.x + 3x .( -2) – [5x.1 + 5x. (- x)] – [8x2 + 8.(- 3)]
= (3x2 – 6x) – (5x – 5x2) – (8x2 – 24)
= 3x2 – 6x – 5x + 5x2 – 8x2 + 24
= ( 3x2 +5x2 – 8x2)- ( 6x + 5x) + 24
= - 11x + 24