Tìm x: a) x^4 - 4x^3 + x^2 - 4x = 0; b) x^2.(x - 1) - 2x.(x - 3) - 9.(x - 1) = 0

Bài 1: Tìm x
a, x^4 - 4x^3 + x^2 - 4x = 0
b, x^2.(x-1) - 2x.(x-3) - 9.(x-1) = 0
c, (5x-1).(3-x) = (x-3).(2x+1)
d, (1+x).(x-2) = (x-2).2x
Bài 2 : Tìm GTLN hoặc GTNN
a, A = -x^2 + 3x - 2
b, B = x^2 + y^2 - 4x - 4y + 6