- #1
1MileCrash
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Homework Statement
I really, really don't understand. My work shows one thing, and a simple look at the function shows another.
f(x,y) = .25x^2 + 5y^7 + 6y^2 - 3x
Find global max and min if they exist.
Homework Equations
The Attempt at a Solution
Took partial derivatives, solved each one for 0.
.5x - 3 = 0 => x = 6
35y^6 + 12y = 0 => y = 0
So a critical point is at (6,0), period.
Discriminant comes out to be
[.5][210y^5 + 12] - 0
Which comes out to be 6, since y = 0.
Therefore the discriminant is > 0, and the partial wrt x is > 0, so a global min occurs at (6,0). Period.
But wait! I submit this answer, and it basically says "nah, forget all that math crap. As y grows without bound, so does the function, so no global max or min."
?
Shouldn't the normal process lead me to that conclusion SOME HOW?