e) x^3 - 4x^2 - 9x + 36
= x^2 ( x - 4 ) - 9 ( x - 4)
= ( x^2 - 9 ) * ( x - 4)
= ( x - 3) ( x + 3) ( x - 4)
g)
=x^2 -2xy+y^2 -(4m^2 -4mn +n^2)
=(x-y)^2 -(2m-n)^2
=(x-y-2m+n)(x-y+2m-n)
f) -4x^2 + 12xy - 9y^2 + 25
= 25 - ( 4x^2 - 12xy + 9y^2)
= 5^2 - ( 2x - 3y)^2
= ( 5 - 2x + 3y)(5+2x-3y)...
cho mk xin hay nhất và cảm ơn nhé