Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 14: Partial Derivatives - Section 14.3 - Partial Derivatives - Exercises 14.3 - Page 807: 49

Answer

$\frac{\partial^{2} w}{\partial x^{2}}$ = $-4x^{3}y^{2}[sin(x^{2}y)]+6xy[cos(x^{2}y)]$ $\frac{\partial^{2} w}{\partial y^{2}}$ = $-x^{5}[sin(x^{2}y)]$ $\frac{\partial^{2} w}{\partial x{\partial y}}$ = $-2x^{4}y[sin(x^{2}y)]+3x^{2}[cos(x^{2}y)]$

Work Step by Step

$\frac{\partial w}{\partial x}$ = $(x)cos(x^{2}y)[y(2x)]+sin(x^{2}y)$ = $2x^{2}y[cos(x^{2}y)]+sin(x^{2}y)$ $\frac{\partial^{2} w}{\partial x^{2}}$ = $-2x^{2}y[sin(x^{2}y)](2xy)+[cos(x^{2}y)](4xy)+cos(x^{2}y)[2xy]$ = $-4x^{3}y^{2}[sin(x^{2}y)]+6xy[cos(x^{2}y)]$ $\frac{\partial w}{\partial y}$ = $(x)cos(x^{2}y)[x^{2}]$ = $x^{3}[cos(x^{2}y)]$ $\frac{\partial^{2} w}{\partial y^{2}}$ = $-x^{3}[sin(x^{2}y)](x^{2})$ = $-x^{5}[sin(x^{2}y)]$ $\frac{\partial^{2} w}{\partial x{\partial y}}$ = $-2x^{2}y[sin(x^{2}y)](x^{2})+[cos(x^{2}y)](2x^{2})+cos(x^{2}y)[x^{2}]$ = $-2x^{4}y[sin(x^{2}y)]+3x^{2}[cos(x^{2}y)]$
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