Reason Behind Math Formula – why (a+b)^2 = a^2 + 2ab + b^2

Everyone knows that (a+b)^2 = a^2 + 2ab + b^

But do you know why?

Think like this – we need to find (a+b)^2 that means we need to find an area of a square with side = a+b.

Lets draw a square with side a+b.


The Square contains 2 square and 2 rectangles.

So Area of Square with Side a + b = area of 2 squares + area of 2 rectangles.



If you add all -> a^2 + ab + ab + b^2 

i.e a^2 + 2ab + b^2

thats why (a+b)^2 = a^2 + 2ab + b^2.

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