Question

Minimize Q=x^2 + 2y^2 where x-y=20?

Answer 1

\[x-y=20\implies y=x-20\]substitute this into Q and take the derivative with respect to x

Answer 2

set that equal to zero and check the endpoints to find max/mins

Answer 3

maybe lagrange can help ?

Answer 4

what?

Answer 5

http://en.wikipedia.org/wiki/Lagrange_multiplier

Answer 6

this is not a multivarible calc problem

Answer 7

2 variables right ?
lagrange can be applied ,,isnt it ?

Answer 8

yes, but why would you want to? this is a simple calc I problem optimizing with a restraint.

Answer 9

hmmm..