Using Properties of Right Triangles

What is the length ‘y’ expressed in terms of ‘x’?

 

a^{2}+b^{2}=c^{2}

x^{2}+x^{2}=(\frac{y}{3})^{2}

\sqrt{2x^{2}}=\sqrt{(\frac{y}{3})^{2}}

\sqrt{2x^{2}}=\frac{y}{3}

3(x\sqrt{2})=(\frac{y}{3})^{3}

y=3x\sqrt{2}