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**brd_7** ts a simple question i think?.. But im not too sure what the answer is myself, which is obviously why im asking...

Ok, the question goes like this

Maximise and Minimise $\displaystyle x^2 +3y^2 $ subject to $\displaystyle x^2 +xy +2y^2 = 56 $.

I understand that i have to differentiate them in respect to x, y, and then lambda.. Rearrange them accordingly to find x and y.

$\displaystyle 2x + \lambda(2x+y) = 0 \, $ Edit: ..... (1)

$\displaystyle 6y+ \lambda(x+4y) = 0 \, $ Edit: .... (2)

$\displaystyle x^2 + xy + 2y^2 -56 = 0 \, $ Edit: .... (3)

Thats what i get.. Not sure where to go from there, i realise that i have to substitute bits in.. but ive tried everything, and cant really seem to get any further. thanks in advance