Question

rút gọn biểu thức ( 9 - 2x )^2 - ( 2x + 3 ) x (3 -2x )

Answer 1

`(9 - 2x)^2 - (2x+3). (3-2x)`

`= (9 - 2x)^2 - ( 3 + 2x).(3 -2x)`

`= 81 - 36x + 4x^2 - (9 - 4x^2)`

`= 81 - 36x + 4x^2 - 9 + 4x^2`

`= (81 - 9 ) + (4x^2 + 4x^2) - 36x`

`= 8x^2 - 36x + 72`

Answer 2

\(\left(9-2x\right)^2-\left(2x+3\right)\left(3-2x\right)\)

\(=4x^2-36x+81+4x^2-9\)

\(=8x^2-36x+72\)