Question

if x and y this find x2+y2

Answer 1

Hi friend!!

Let given two variables be x and y .

We know that (x+y)²=x²+y²+2xy

→(x+y)²-2xy=x²+y²


So, x²+y²=(x+y)²-2xy ----(1)

And also, (x-y)²=x²+y²-2xy

→(x-y)²+2xy=x²+y²

So, x²+y²=(x-y)²+2xy-----(2)

Adding (1) and (2), we get

2(x²+y²)=(x+y)²+(x-y)²+2xy-2xy


2(x²+y²)=(x+y)²+(x-y)²

x²+y²=[(x+y)²+(x-y)²]/2

I hope this will help u :)