(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

1. for the surface z=9 - x^2 - y^2 find,

i) the gradient at (1,1,7) in the direction making an angle alpha with the x axis

ii) the max gradient at the point (1,1,7) and the value of alpha for which it occurs

2. find the stationary point of z=x^2 +2x +3y^2 -3xy + 5 and determine the nature of this point

2. Relevant equations

this is what i need, im not sure of the equation you use to differentiate an equation like this.

3. The attempt at a solution

I know you have to partially diff it with respect to x and then with respect to y,

but I don't know how to combine the 2 together so you can just put the numbers in and find the gradient.

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# Gradient of a two term equation

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