If y^4 + 1y^4 = 223 and y > 1, then find the value of y^2 + 1y^2?

Answer: Option A

$$\begin{array}{rl}& y^4+\frac{1}{y^4}=223\\ & \Rightarrow y^2+\frac{1}{y^2}=\sqrt{223+2}\\ & \Rightarrow y^2+\frac{1}{y^2}=\sqrt{225}\\ & \Rightarrow y^2+\frac{1}{y^2}=15\end{array}$$