Lagrange Multiplier Problem

**Solve the following problem using Lagrange multipliers. 1.) Find the critical points of** f(x,y)= **on the curve** .

Thus, yeilding my three equations with three unknowns:

Solving the equations, I get the following:

Plugging these into the third equation yeilds:

This is where I'm stuck, how can (a positive number) plus (also a positive number) = -1 when added together. Can someone help me find my mistake so I can finish the problem? Thanks

Re: Lagrange Multiplier Problem

Quote:

Originally Posted by

**dbakeg00**

Right.

It should be

Right.

Re: Lagrange Multiplier Problem

The derivative of with respect to y, as FernandoRevilla suggests, is NOT "x" but . Write as and it should be easy to see why.

Re: Lagrange Multiplier Problem

Re: Lagrange Multiplier Problem

Thanks Fernando & Halls...that was a dumb mistake which I should have caught. Soroban, I'll have to study your way for a bit and see how I like it. Thanks again to all for the help.