Rút gọn biểu thức: A = (3x - y).(3x + y) + (x - y)^2; B = (2x + 3).(2x - 3) - (x - 3)^2 + (2x - 1).(x + 2)
Rút gọn biểu thức
A = (3x - y).(3x + y) + (x - y)^2
B = (2x + 3).(2x - 3) - (x - 3)^2 + (2x - 1).(x + 2)
C = (2x - 1)^2 - 2.(2x - 1).(x + 1) + (x + 1)^2