Đáp án:
Giải thích các bước giải
a) x²-y²-2x+2y= (x-y)(x+y)-2(x-y)= (x-y)(x+y-2)
b)2x+2y-x²-xy= 2(x+y)-x(x+y)= (2-x)(x+y)
c)3a²-6ab+3b²-12c²= 3(a²-2ab+b²)-12c²= 3(a-b)²-12c²= 3[(a-b)²-(2c)²]=3(a-b+2c)(1-b-2c)
d)x²-25+y²+2xy= x²+2xy+y²-5²=(x+y)²-5²=(x+y+5)(x+y-5)
e)a²+2ab+b²-ac-bc= (a+b)²-c(a+b)= (a+b)( a+b-c)
f)x²-2x-4x²-4y= -3x²-2x-4y= -(3x²+2x+4y)
g)x²y-x³-9y+9x= x²(y-x)-9(y-x)= (y-x)(x²-9)
h) x²(x-1)+16(1-x)= x²(x-1)-16(x-1)= (x-1)(x²-16)= (x-1)(x-4)(x+4)
n)81x²-6yz-9y²-z²= (9x)²-[(3y)²+6yz+z²]=(9x)²-(3y+z)²=(9x+3y+z)(9x-3y-z)
m) xz- yz-x²+2xy-y²= z(x-y)-(x²-2xy+y²)= z(x-y)-(x-y)²= (x-y)(z-x+y)