Question

将下列多项式分解因式 x²-7xy+12y² 4m²+8mn+3n² x²-（a+b)xy+aby² x²

知道的人回答下吧！

Answer 1

（1）原式=(x-3y)(x-4y)
(2)原式=(2m+3n)(2m+n)
(3)原式=(x-ay)(x-by)
你只有三道题，后面的没写全

Answer 2

x²-7xy+12y²
=x²-3xy-4xy+12y²
=x(x-3y)-4y(x-3y)
=(x-3y)(x-4y)

4m²+8mn+3n²
=4m²+6mn+2mn+3n²
=2m(2m+3n)+n(2m+3n)
=(2m+3n)(2m+n)

x²-（a+b)xy+aby²
=x²-axy-bxy+aby²
=x(x-ay)-by(x-ay)
=(x-ay)(x-by)