Question

1.2*（x+y）^2+(x+y)(c+d)-6（c+d）^2

Answer 1

1.2*（x+y）^2+(x+y)(c+d)-6（c+d）^2 令k=x+y ,h=c+d原式=2k^2+kh-6h^2=(2k-3h)(k+2h)=(2x+2y-3c-3d)(x+y+2c+2d).2.21a^2-13ab+2b^2 =(3a-b)(7a-2b).3.(x-y)^2-3(x-y)-10令k=x-y原式=k^2-3k-10=(k-5)(k+2)=(x-y-5)(...