Question

(a+b)2 +(a-b)2=2 (a2+b2) 2)(a+b)2-(a-b)=4ab
3)(a+b+c)2=a2+b2+c2+2a×b+2a×c+2b×c

Answer 1

2а+2б+2а-2б=4а
2а+2б+2с