

Báo cáo sai phạm
a, A = 27x3 + 54x2 + 36x + 4
=> A = (3x)3 + 2 . 3 . 9x2 + 3 . 3x . 4 + 8 - 4
=> A = [(3x)3 + 2 . 3 . (3x)2 + 3 . 3x . 22 + 23] - 4
=> A = (3x + 2)3 - 4
Thay x = -2002 vào A ta có: A = (3x + 2)3 - 4
=> A = [3 x (-2002) + 2]3 - 4 = [6006 + 2]3 - 4 = 60083 - 4
b, B = 2x2 + 4x + xy + 2y
=> B = 2x(x + 2) + y(x + 2)
=> B = (x + 2)(2x + y)
Thay x = 88; y = -76 vào B
=> B = (88 + 2)[2 . 88 + (-76)]
=> B = 90 . [176 + (-76)] = 90 . 100 = 9000