1-20题只写答案就行,21题化简,22题先化简再求值,快,其中√为根号

1-20题只写答案就行,21题化简,22题先化简再求值,快,其中√为根号
1.(1-mn)(mn+1)= 2.(-1/2x+3y)(-3y-1/2x)=
3.(-a+b²)(-a-b²)= 4.(a²+5ab)(5ab-a²)=
5.(a的n次方+b）×（b-a的n次方)= 6.(a+1)(a-1)(1+a²)=
7.1225-75²= 8.51×49=
9.(-1001)×(-999)= 10.(2x-3(-2x-3)-x(x-1)=
11.(a-b+c)(a+b-c)= 12.(x+y)(x-y)(-x=y)(-x-y)=
13.(2m+n)²= 14.(-2m+n)²=
15.(-1/3x-3y)²= 16.(a+b)²-(a-b)²=
17.(2x+y)²+(y-2x)²= 18.999²
19.(x+y)（x-y）(x²-y²)= 20.(x²-2y)²-(x²+2y)²=
21.{（a-b)(a+b)}²-(a²+ab+b²)(a²-ab+b²)+4a²b²(b-1)(b+1) 此题化简
22.{x-y+（4xy/x-y）}×{x+y-(4xy/x+y)}-x ² 其中x ²=2（√2）+3,y²=π-3