0 votes 0 votes The magnitude of the directional derivative of the function $f(x,y)=x^2+3y^2$ in a direction normal to the circle $x^2+y^2=2,$ at the point $(1,1),$ is $4\sqrt{2}$ $5\sqrt{2}$ $7\sqrt{2}$ $9\sqrt{2}$ Calculus gate2015-in calculus directional-derivatives + – Milicevic3306 asked Mar 26, 2018 • recategorized Mar 20, 2021 by Lakshman Bhaiya Milicevic3306 7.9k points answer See all 0 reply