a. (a+b).(a+b)
= a+b.a+b
= (a+b)2
b, (a-b).(a-b)
= a-b.a-b
= (a-b)2
a,(a+b).(a+b)
=(a+b).a+(a+b).b
=a2+ba+ab+b2
=(a2+b2)+2ab
b,(a-b).(a-b)
=(a-b).a-(a-b).b
=a2-ba-ab-b2
=(a2-b2)-(ab-ba)
=a2-b2
a)(a+b)(a+b)=a(a+b)+b(a+b)=a2+ab+ab+b2=a2+2ab+b2
b)(a-b)(a-b)=a(a-b)-b(a-b)=a2-ab-ab+b2=a2-2ab+b2