Question

[đăng quang hồ]

Bài 2: Rút gọn  các biểu thức sau:

     a.(x-3)(x + 7) – (x +5)(x -1)                        b. (x + 8)² – 2(x +8)(x -2) + (x -2)²

     c. x²(x – 4)(x + 4) – (x² + 1)(x²- 1)               d. (x+1)(x² – x + 1) – (x – 1)(x² +x +1)

Answer 1

[Nguyễn Hoàng Minh]

\(a,=x^2+4x-21-x^2-4x+5=-16\\ b,=\left(x+8-x+2\right)^2=10^2=100\\ c,=x^2\left(x^2-16\right)-\left(x^4-1\right)\\ =x^4-16x^2-x^4+1=1-16x^2\\ d,=x^3+1-x^3+1=2\)