Đáp án+Giải thích các bước giải:
$a) 3x-3y+x²-y²$
$=3(x-y)+(x-y)(x+y)$
$=(x-y)(3+x+y)$
$b) (2xy+1)²-(2x+y)²$
$=[(2xy+1)-(2x+y)].[(2xy+1)+(2x+y)]$
$=(2xy+1-2x+y).(2xy+1+2x+y)$
$=(y+1)(2x+1)(y-1)(2x-1)$
$c) (x²+y²-5²)²-4 (x²y²+4xy+4)$
$=(x²-y²-2y-1)(x²-2xy+y²-9)$
$=[x²-(y²+2y+1)](x²-2xy+y²-9)$
$=[x²-(y+1)²][(x-y)²-3²]$
$=[x²-(-y-1)²](x-y-3)(x-y+3)$
$=(x+y+1)(x-y-1)(x-y-3)(x-y+3)$
Chúc bn hc tốt🥰
$\text{#LinhSad}$