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- #1

- Apr 13, 2013

- 3,720

Let $(x,3)=(y,3)=1$.Show that $x^2+y^2$ is not a square.How can I do this?

I thought that I could use these relations:

$$ax+3b=1$$

$$yc+3d=1$$

But,using them I found: $x^2+y^2=\frac{cx(1-3b)+ay(1-3d)}{ac}$.. I think that we can't conclude it from this..or am I wrong??