\(\left(1+2x\right).\left(1-2x\right)-x.\left(x+2\right).\left(x-2\right)\))
\(=1-\left(2x\right)^2-x.x^2-2^2\)
\(=1-4x^2-x^3-4\)
Ko bt có đúng ko nữa
( 1 + 2x ) ( 1 - 2x ) - x ( x + 2 ) ( x - 2 )
= 1 - 4x2 - x ( x2 - 4 )
= 1 - 4x2 - x3 + 4x
= - ( x3 + 4x2 - 4x - 1 )
= - ( x3 - x2 + 5x2 - 5x + x - 1 )
= - [ x2 ( x - 1 ) + 5x ( x - 1 ) + ( x - 1 ) ]
= - ( x - 1 ) ( x2 + 5x + 1 )