Question

(a+b)=a^2+2ab+b^2
what is this

Answer 1

It's a formulae ......

Answer 2

It's a formula
It is actually (a+b) ²

Take a square. Divide the square vertically into two parts by drawing a straight line. The lengths of them are $a$ and $b$ respectively.

Divide the square horizontally into two parts by drawing a straight line but the lengths of them should also be $a$ and $b$ respectively.

The length of whole square is $a+b$ and width of this square is also $a+b$. Therefore, the area of the square is $(a+b) × (a+b) \,=\, {(a+b)}^2 geometrically.