\(1)\left(a+b\right)\left(a+b\right)\)
\(=a\left(a+b\right)+b\left(a+b\right)\)
\(=a^2+ab+ba+b^2\)
\(2)\left(a-b\right)\left(a-b\right)\)
\(=a\left(a-b\right)-b\left(a-b\right)\)
\(=a^2-ab-ba-b^2\)
\(3)\left(a-b\right)\left(a+b\right)\)
\(=a\left(a+b\right)-b\left(a+b\right)\)
\(=a^2+ab-ba+b^2\)
1, (a+b)(a+b) = (a + b)2
2, (a-b)(a-b) = (a - b)2
3, (a-b)(a+b) = a2 - b2
4, (a+b)(a+b)(a+b) = (a +b)3
5, (a-b)(a-b)(a-b) = (a - b)3
6) ( a+b)(a2 - ab + b2) = a3 + b3
7) (a-b)(a^2+ab+b^2) = a3 - b3