Write the given ODE in the form (1) if it is in a different form (Use Prob, $6 .$ ) Find the cigenvalues and cigen functions. Verify orthogonality. (Show the details of your work.)
$$\begin{aligned}
&y^{\prime \prime}+\lambda y=0, \quad y(0)+y^{\prime}(0)=0\\
&y(1)+y^{\prime}(1)=0
\end{aligned}$$