Question

Taking a,b,c as positive integers,verify the following whether they are idehtities or not? 1.(a-b)²=a²-2ab+b²
2.(a+b)(a-b)=a²-b²
3.(a+b+c)²=a²+b²+c²+2ab+2bc+2ca​

Answer 1

Answer:

(a_b)×(a-b)=a×a-ab-ab+(-b×-b)

then -×-=+but put the same sign