Given,
$$x - y = 13$$ and $$xy = 25$$
$$=$$> Â $$\left(x-y\right)^2=13^2$$
$$=$$> Â $$x^2+y^2-2xy=169$$
$$=$$> Â $$x^2+y^2+2xy-4xy=169$$
$$=$$> Â $$\left(x+y\right)^2-4xy=169$$
$$=$$> Â $$\left(x+y\right)^2-4\left(25\right)=169$$
$$=$$> Â $$\left(x+y\right)^2-100=169$$
$$=$$> Â $$\left(x+y\right)^2=269$$
$$=$$> Â $$x+y=\sqrt{269}$$
$$\therefore\ $$ $$x^2-y^2=\left(x+y\right)\left(x-y\right)=\left(\sqrt{269}\right)\left(13\right)=13\sqrt{269}$$
Hence, the correct answer is Option C
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