# Tagged Questions

Questions on fractions, which are expressions (not values) of the form $\frac pq$.

61 views

### Find the limit of fraction involving logarithms

I am looking for a way to prove the following limit for integer $x$s: $$\lim_{x\to\infty}{\frac{\log(x+2)-\log(x+1)}{\log(x+2)-\log(x)}}=\frac{1}{2}$$ I could find the result by using a computer ...
30 views

### Stern-Brocot Tree and sum of coefficients of continued fraction

Suppose we are given a continued fraction $$\frac{p}{q}=a_{1}+\frac{1}{a_{2}+\frac{1}{a_{3}+\frac{1}{a_{4}+\cdots}}}$$ I am trying to find an expression, possibly asymptotic, for the sum of the $a_i$'...
67 views

42 views

24 views

### About a largest integral value of this sum of reciprocal numbers.

In a test , I was asked to solve the following question : If $a_1,a_2,a_3, \cdots ,a_n$ are $n$ distinct odd natural numbers and not divisible by any prime number greater than equal to $7$ . Then the ...
62 views

### Solve fractions multiplication

I believe this is a very simple one, but I simply can't figure it out. How to solve? $$\frac12\cdot\frac34\cdot\frac56\cdots\frac{17}{18}\cdot\frac{19}{20}$$
73 views

### Laurent expansion of $\frac{1}{z^2}$

I need to find a Laurent expansion of $\frac{1}{z^2}$ with centre in $z_0 = 1$ and $P(1, 2014, 2015)$. If it was $\frac{1}{z}$, I'd rewrite the fraction like this: $$\frac{1}{(z-1) +1 }$$ But ...
80 views

### How do I show that $-\frac{1}{e^x + 1} + 1 = \frac{e^x}{e^x + 1}$?

The expression is $$-\frac{1}{e^x + 1} + 1 = \frac{e^x}{e^x + 1}$$ I would like help to get from the left side to the right side.
53 views

### If the chance of an event was $1/128$ and increased by $20\%$, what is the new chance?

So I have something that has a 1/128 chance of occurring, let's say. Suddenly, the chances of that thing happening are increased by 20%. How is that fraction written? Would you multiply 1/128 by 6/...
51 views

40 views

### Dividing factorials

I'm told that $\dfrac{(n+1)!}{(n+2)!}$ simplifies to $\dfrac{1}{n+2}$, but I dont understand how this works. Could someone explain the theory of how to divide factorials like this?
41 views

### What rule is used for this simplification?

$$\frac{8}{(s+1)^2 + 2^2} \times \frac{1}{s} = \frac{8}{5} - \frac{1}{s} + \frac{16}{10}\times \frac{s+1}{(s+1)^2 + 2^2} + \frac{8}{10}\times \frac{2}{(s+1)^2 + 2^2}$$
27 views

### Help Solving Fraction Math Question

Im stumped by this question on a practice ACT math test. If $\frac 1x + \frac 1y = \frac 1z$ then $z =$? The correct answer is $\frac {xy}{x + y}$ How do you arrive at this answer? I don't know how ...
22 views

86 views

### How to explain aspects of derivatives to little brother?

So as the title suggests, my $12$ year old little brother loves math. Since he is a bright kid, I started teaching him derivatives. The issue is he always keeps asking weird questions that are above ...
### Why is $\left(\frac{1}{2}\right)^{x} = \frac{1}{7}$ the same as saying: $(2)^{x} = 7$
Why is $\left(\frac{1}{2}\right)^{x} = \frac{1}{7}$ the same as saying: $(2)^{x} = 7$ Sorry for the really dumb question but I'd like to see the process of how this is achieved.