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kscplay
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Homework Statement
f(x) = (1-x3)(2+x4)(3-x5)(4+x6)(5-x7)(6+x8)...(2n+1-x2n+3)
Find f ' (1).
Homework Equations
The Attempt at a Solution
f (1) = 0 because of the first term. Also the pattern is that terms with odd numbers have a subtraction sign and terms with even numbers have an addition sign.
I used logarithmic differentiation ("a" & "b" denote the terms of the original function in order to avoid rewriting all that):
ln y = ln a + ln b ...
y' * (1/y) = (1/a) + (1/b)...
y' = [(1/a) + (1/b)] * [y]
y'(1) = [(1/a) + (1/b)] * [y(1)
Since we already know y(1) = 0, y'(1) also equals 0.
Is this correct? Any help is much appreciated.
Edited: I just noticed that after differentiating, my first term would be [1/(1-x3)] and plugging 1 to x would give a fraction where 0 is the denominator. I guess that makes my solution incorrect?
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