Cho M = (x – 3)3 – (x + 1)3 + 12x(x – 1). a) Rút gọn M.
Cho M = (x – 3)3 – (x + 1)3 + 12x(x – 1).
a) Rút gọn M.
a) Ta có:
M = (x – 3)3 – (x + 1)3 + 12x(x – 1)
M = x3 – 9x2 + 27x – 27 – x3 – 3x2 – 3x – 1 + 12x2 – 12x
M = 12x – 28.