初中乘法公式的一些题目

1.（5-3m)²
2.(-5ayz+1/5a²)²
3.(a+b)²(a-b)²(a²+b²)²
4.（a-b-c)²
5.(2a+3b-4c)²
6.(a+b+c+d)(a+b-c-d)
7.(a+b+c+d)²
8.(x+y)(x-y)
9.(3x+2y)(3x-2y)
10.(-3x+2y)(-3x-2y)
11.(7mn²-8cd²)(7m²n+8cd²)
12.1/5(30a²+15b²)(6a²-3b²)
13.(x+2y-3)(x-2y+3)
14.(x+1/x)²-(x-1/x)²
15.(2a-b)²-2b²
16.(5m+3n)²-(2m-n)²
17.[(a+b)²+(a+b)²](a²-b²)
18.(a-2b+3c-1)(a-2b-3c+1)
19.(p+2z)²-2(p+2z)(p+3z)+(p+3z)²
20.(-mn+ab)²
21.(3x-1/2y)²
22.（-1/3m²n+3/4mn²)²
23.已知(a-b)²=7,（a+b)²=13求a²+b²,ab的值。
要完整的过程才能给分
快快快 在8：30之前。

1.（5-3m)²=25-30m+9m^2

2.(-5ayz+1/5a²)²=25a^2y^2z^2-2*5ayz*1/5a^2+1/25a^4=25a^2y^2z^2-2a^3yz+1/25a^4

3.(a+b)²(a-b)²(a²+b²)²
=[(a^2-b^2)]^2(a^2+b^2)^2
=(a^4-b^4)^2
=a^8-2a^4b^4+b^8

4.（a-b-c)²
=[a-(b+c)]^2
=a^2-2a(b+c)+(b+c)^2
=a^2-2ab-2ac+b^2+2bc+c^2

5.(2a+3b-4c)²
=4a^2+4a(3b-4c)+(3b-4c)^2
=4a^2+12ab-16ac+9b^2-24bc+16c^2

6.(a+b+c+d)(a+b-c-d)
=[(a+b)+(c+d)][(a+b)-(c+d)]
=(a+b)^2-(c+d)^2
=a^2+2ab+b^2-c^2-2cd-d^2

7.(a+b+c+d)²
=(a+b)^2+2(a+b)(c+d)+(c+d)^2
=a^2+2ab+b^2+2ac+2ad+2bc+2bd+c^2+2cd+d^2

8.(x+y)(x-y)
=x^2-y^2

9.(3x+2y)(3x-2y)
=9x^2-4y^2

10.(-3x+2y)(-3x-2y)
=9x^2-4y^2

11.(7mn²-8cd²)(7mn^2+8cd²)
=49m^2n^4-64c^2d^4

12.1/5(30a²+15b²)(6a²-3b²)
=1/5*5(6a^2+3b^2)(6a^2-3b^2)
=36a^4-9b^4