- #1
Cade
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Homework Statement
Find a point where f(x,y) = x^2 + 4xy + 3y^2 < 0
Homework Equations
Turning points are where df/dx = 0 and df/dy = 0
The Attempt at a Solution
df = (2x + 4y)dx + (4x + 6y)dy
2x + 2y = 0, 4x + 6y = 0 -> turning point at (0,0)
From this step, how can I find a point (x,y) where f(x,y) is negative?