Question Number 130976 by BHOOPENDRA last updated on 31/Jan/21
$${if}\:{U}={f}\left({x},{y},{z}\right){and}\:{z}={f}\left({x},{y}\right){then}\:{find}\: \\ $$$${the}\:{formula}\:\frac{{d}^{\mathrm{2}} {u}}{{dx}^{\mathrm{2}} }\:{in}\:{terms}\:{of}\:{derivetive} \\ $$$${of}\:{F}\:{and}\:{derivative}\:{of}\:{z}\:{respectively}? \\ $$