Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.
Trending News
Minimum Value Question: You definitely can't use Calculus here!?
Find the minimum value of f(x)=abs(x-1)+abs(x-1)+abs(x-2)+...abs(x-144), where each number corresponds to each Fibonacci number.
Sorry, somehow part of the question got erased: It's to abs(x-144)....I'm really sorry about that=(
and, x is any real number.
2 Answers
- MathsorcererLv 71 decade agoFavorite Answer
Are there any restrictions on x? If no, then there is no "minimum" value because the sums will always approach infinity.
f(x) = |x-1| + |x-1| + |x-2| + |x-3| + |x-5| + |x-8| + ...
If you pick any value of x, you will find that your results are just that far away from the regular Fibonacci numbers.
Let x = 1.7; f(1.7) = 0.7 + 0.7 + 0.3 + 1.3 + 3.3 + 6.3 + 11.3... and if you keep adding to infinity then the sum becomes infinity.
By the way, you *can* use calculus on this function...with some restriction.
Suppose x is a really large positive number. This means that
f'(x) = 1 + 1 + 1 + 1 + 1.... you will have a string of +1s before x and then -1s afterward; since there are infinitely many more numbers *larger* than x then f'(x) --> -∞.
- Randy PLv 71 decade ago
Maybe I'm missing something here. It seems to me this is a diverging series.
The Fibonacci numbers grow without bound. So no matter what x you pick, there are infinitely many Fibonacci numbers greater than x. Not only are they greater than x, they are greater than x + 1. So there are infinitely many Fibonacci numbers F_n such that |x - F_n| > 1
That means you have an infinite series with all terms positive and infinitely many terms greater than 1. So it diverges. f(x) is infinite for all x.
Did I misunderstand something?