f(x)=Sq. root of x^2+18x+86
2007-07-28 06:22:36 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
f(x) = (x^2 + 18x + 86)^(1/2)
f'(x) = 1/2 * (2x + 18) * (x^2 + 18x + 86)^(-1/2)
This is zero when 2x + 18 = 0
x = -9
You also need to verify that x = -9 does not set the denominator equal to zero, which it doesn't.
2007-07-28 06:31:13 · answer #1 · answered by Dr D 7 · 1⤊ 0⤋
f(x)=Sq. root of x^2+18x+86
f'(x) = {.5(x^2+18x +86)^-.5}(2x+18)
Seting f'(x) to 0 gives x = -9
2007-07-28 06:33:08 · answer #2 · answered by ironduke8159 7 · 0⤊ 0⤋
You don't even need to take derivative for the problem.
x = -18/2 = -9
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Reason: x^2+18x+86 represents a parabola which has its minimum at x = -b/(2a).
2007-07-28 06:31:57 · answer #3 · answered by sahsjing 7 · 0⤊ 0⤋
Take the derivative and set it equal to zero. solve for 'x'
2007-07-28 06:25:47 · answer #4 · answered by nhaisma 2 · 0⤊ 0⤋
wow, i was gonna say -9 too, but I wasn't sure if it was right, guess I surprised myself, lol!
2007-07-28 06:44:41 · answer #5 · answered by Joe E 2 · 0⤊ 0⤋