Project ForgeEngineering Mathematics
Linear Algebra
GATE 2019
Medium
The directional derivative of u(x,y,z)=x²−3yz at the point (2,0,−4) in the direction (i+j−2k)/√6 is (rounded off to two decimal places)
6.53(± 0.03 accepted)
Explanation
∇u=(2x,−3z,−3y)=(4,12,0) at (2,0,−4). Directional derivative=∇u·(1,1,−2)/√6=(4+12+0)/√6=16/√6=6.53.
Source: GATE CH 2019 (2019)
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