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Whats the abs max and min ofthis problem : f(x) = x^2 + (432/x)

2007-04-09 15:44:33 · 2 answers · asked by lindsay e 1 in Science & Mathematics Mathematics

2 answers

Just take the derivative:
f'(x) = 2x - (432/x^2)
Set this equal to 0.
2x - (432/x^2) = 0.
x = 6
Now, to figure out if it's a max or min, test regions.
x < 6, so test -7 in f'(x), and you get a negative answer.
x > 6, so test 7 in f'(x) and you get a positive answer. Because the derivative is going from a - to a +, 6 is a rel. min.

Edit: I did relative min... no clue why, sincerest apologies. I need to learn to read.

2007-04-09 15:52:28 · answer #1 · answered by Brad 2 · 0 0

"Absolute max" is ∞ at x = -∞, 0+, and +∞
Absolute min is -∞ at x = 0-

2007-04-09 16:02:11 · answer #2 · answered by Helmut 7 · 0 0

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