1
GATE CE 1995
MCQ (Single Correct Answer)
+1
-0.3
The derivative of $$f(x, y)$$ at point $$(1, 2)$$ in the direction of vector $$\overrightarrow i + \overrightarrow j $$ is $$2\sqrt 2 $$ and in the direction of the vector $$ - 2\overrightarrow j $$ is $$-3.$$ Then the derivative of $$f(x,y)$$ in direction $$ - \overrightarrow i - 2\overrightarrow j $$ is
A
$$2\sqrt 2 + 3/2$$
B
$$ - 7/\sqrt 5 $$
C
$$ - 2\sqrt 2 - 3/2$$
D
$$ 1/\sqrt 5 $$
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Fluid Mechanics and Hydraulic Machines
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