1. Literal Formula Question

Hi, I have two (basic) questions that I cant seem to understand. I'm in a self taught course where I learn everything from a book so it might have not explained everything fully. Question #1. $\displaystyle p = 2hw/(s+1)$ solve s. My answer to the question is $\displaystyle s = -1 + 2hw/p$ however I've been told the correct answer is $\displaystyle s = -p + 2hw/p$. My question is, why are there two P's now instead of 1? Can anyone explain that to me? Thank you.

3. Re: Literal Formula Question

Originally Posted by Robert12
Hi, I have two (basic) questions that I cant seem to understand. I'm in a self taught course where I learn everything from a book so it might have not explained everything fully. Question #1. $\displaystyle p = 2hw/(s+1)$ solve s. My answer to the question is $\displaystyle \color{blue} s = -1 + 2hw/p$ however I've been told the correct answer is $\displaystyle \color{red}s = -p + 2hw/p$. My question is, why are there two P's now instead of 1? Can anyone explain that to me? Thank you.

4. Re: Literal Formula Question

Interesting, this isnt the first time I've seen that however. One of the questions in my book: $\displaystyle M = 2T/g+a$ for a is similar, the answer given is $\displaystyle a = 2T - gM/M$. My answer: $\displaystyle a = 2T - gM$ If this is another mistake could anyone provide an example where I could get an answer of two of the same variable from one incase I see it on a test? Thank you for the quick responses.

5. Re: Literal Formula Question

Originally Posted by Robert12
Interesting, this isnt the first time I've seen that however. One of the questions in my book: $\displaystyle M = 2T/g+a$
This one is quite simple, solve for 'a'

$\displaystyle M = 2T/g+a$

$\displaystyle M - 2T/g = a$

And we are done.

What do you mean by

Originally Posted by Robert12
If this is another mistake could anyone provide an example where I could get an answer of two of the same variable from one

6. Re: Literal Formula Question

Originally Posted by Robert12
Interesting, this isnt the first time I've seen that however. One of the questions in my book: $\displaystyle M = 2T/g+a$ for a
Given $\displaystyle M=\frac{2T}{g+a}$ that is the same as
\displaystyle \begin{align*} g+a &= \frac{2T}{M} \\ a &= \frac{2T}{M}-g\end{align*}

7. Re: Literal Formula Question

Just double check whether or not the given answers are the solutions
to the following (should you have had parenthesis around certain numerators and denominators).

$\displaystyle p=\frac{2hw}{s+1}$

$\displaystyle p(s+1)=2hw\Rightarrow\ ps+p=2hw\Rightarrow\ ps=2hw-p$

$\displaystyle s=\frac{2hw-p}{p}$

which is the same as

$\displaystyle s=\frac{2hw}{p}-\frac{p}{p}$

For the 2nd one....

$\displaystyle M=\frac{2T}{g+a}$

$\displaystyle M(g+a)=2T\Rightarrow\ Mg+Ma=2T$

$\displaystyle Ma=2T-Mg$

$\displaystyle a=\frac{2T-Mg}{M}$

8. Re: Literal Formula Question

Wow, thank you Archie and everyone else. It makes complete sense now. You were right about the parenthesis which is why my answers were formatted a bit differently. I'll keep it in mind when solving questions like that again.

Edit: I can see there are 3 different answers for the 2nd question. I'm going to by the one Archie has since its in my solutions but is there generally more then one way to solve questions like that? Or was this just a simple mistake of not using parenthesis?