Question

1:分解因式4(x+2y)²-25(x-y)²=...2:把9(x-y)+12(x²-y&

Answer 1

(x+2y)²-25(x-y)²

=(x+2y+5x-5y)(x+2y-5x+5y)

=(6x-3y)(7y-4x)

=3（2x-y)(7y-4x)

9(x-y)²+12(x²-y²)+4(x+y)²

=(3x-3y+2x+2y)^2

=(5x-y)^2

(x+y)^m+1-(x+y)^m-1

=(x+y)^m-1(x+y+1)(x+y-1)

-3y^4+10y²+8

=-(3y^2+2)(y^2-4)

=-(3y^2+2)(y+2)(y-2)