Toán Lớp 8: Bài 1: Tính
a) (5x + 3yz)2
b) (y2x – 3ab)2
c) (x2 – 6z)(x2 + 6z)
d) (2x – 3)3
e) (a + 2b)3
g) (x2 + 3)(x4 + 9 – 3×2)
h) (y – 5)(25 + 2y + y2 + 3y)
Bài 2: Rút gọn biểu thức:
a) B = (x + y)2 – 2(x + y)(x – y) + (x – y)2
= x2 + 2xy + y2 – 2×2 + 2y2 + x2 – 2xy + y2 = 4y2
b) C = (x + y)3 – (x – y)3 – 2y3