AP EAMCET Engineering 2011 Solved Paper

u=sin(y+ax)−(y+ax)2 ......(i)
On differentiating partially w.r.t. x, we get
ux=cos(y+ax)‌a−2(y+ax)a
Again differentiating partially w.r.t. x, we get
uxx=−sin(y+ax)‌a2−2a2 ........(ii)
On differentiating partially Eq. (i) w.r.t. y,we get
uy=cos(y+ax)−2(y+ax)
⇒ uyy=−sin(y+ax)−2 .......(iii)
∴ From Eqs. (ii) and (iii), we get
uxx=a2uyy