Let $z = \sqrt { x ^ { 2 } + y ^ { 2 } }$

Essay

Let $z = \sqrt { x ^ { 2 } + y ^ { 2 } }$ , $x = s ^ { 2 } - t ^ { 2 }$ , and $y = 2 s t$ . Use the chain rule to find $\frac { \delta z } { \delta s }$ and $\frac { \delta z } { \delta t }$ .