Question

a²+b²-2ab-1 因式分解

还有1-25b²
25（a+b)-9(a-b)²
-x²-4y²+4xy
4xy³+4x²y²+xy³
9x²(a-b)+y²(b-a)

Answer 1

1.(a-b+1)(a-b-1)
2.(1-5b)(1+5b)
3.[5(a+b)-3(a-b)][5(a+b)+3(a-b)]
4.-(x-2y)2
5.应该是4x3y+4x2y2+xy3吧，应该是xy(2x+y)2
6.(a-b)(3x+y)(3x-y)

Answer 2

a²+b²-2ab-1
=(a-b)²-1²
=(a-b+1)(a-b-1)

1-25b²
=(1-5b)(1+5b)

25（a+b)-9(a-b)²
=25(a+b)-9(a-b)(a+b)
=(a+b)(25-9a+9b)

-x²-4y²+4xy
=(x-2y)(2y-x)

4xy³+4x²y²+xy³
=xy(4x²+4xy+y²)
=xy(2x+y)²

9x²(a-b)+y²((b-a)
=(9x²-y²)(a-b)
=(3x-y)(3x+y)(a-b)