For the function f(x,y) = 2x^3 + 3xy + 2y^3,

if the values of c and y are constrained to lie on the straight line y+x=1 use the lagrange multiplier method to find the value of (x,y) where f(x,y) has a turning point.

So far I have computed f sub x, f sub y and f sub lambda to produce 3 equations which imply that y=1-x,

6x^2 + 3 -3x + lambda =0 and

6x^2 - 9x + 6 + lamda = 0

at this point I get stuck