#### Answer

True

#### Work Step by Step

Since, D_{k}f(x,y,z)=∆ f.k$
$=[f_{x}(x,y,z),f_{y}(x,y,z),f_{z}(x,y,z)].(0,0,1)$
$=f_{z}(x,y,z)$
Hence, the statement is true.

Published by
Cengage

ISBN 10:
1285740629

ISBN 13:
978-1-28574-062-1

True

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