\(2ax^2-bx^2-2ax+bx+4a-2b\)
\(=\left(2ax^2-2ax+4a\right)-\left(bx^2-bx+2b\right)\)
\(=2a\left(x^2-x+2\right)-b\left(x^2-x+2\right)\)
\(=\left(2a-b\right)\left(x^2-x+2\right)\)
Tiếp đi~~
2ax2 - bx2 - 2ax + bx + 4a - 2b
= (2ax2 - 2ax + 4a) - (bx2 - bx + 2b)
= 2a.(x2 - x + 2) - b.(x2 - x + 2)
= (x2 - x + 2).(2a - b)
= (x2 - 2x + x + 2).(2a - b)
= [-x.(x + 2) + (x + 2)].(2a - b)
= (x + 2).(1 - x).(2a - b)