Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Ok thats very basic but dont get it , I have the following equation $R-A X-B \dfrac{A X}{2 B}=0$ the right result of it is $R- \dfrac{3 A X}{2}=0$

well, now when I attempt to solve it I do the following: $A X+\dfrac{A X}{B}=R$, so what I have done here is cancel the $B$ that is multiplying with one of the $B$'s which are dividing, I don't see why that is wrong, but I guess that's where I make the mistake.. Can anyone tell me why please? Cheeers!

share|improve this question
1  
"one of the B's"? There's more than one B dividing? –  User58220 Apr 3 '13 at 0:17
    
yeah well is divided by 2*B , so B*B, 2 B's. cheers –  Maximilian1988 Apr 3 '13 at 0:18
1  
2*B is not the same as B*B. –  Code-Guru Apr 3 '13 at 0:29

2 Answers 2

up vote 1 down vote accepted

2*B is not B squared, it is just 2 times B. So you have one B in the numerator and one in the denominator, and they cancel completely. There is no B left in the denominator after the cancellation. But there is a "2".

share|improve this answer
    
goooosh...embarrassed... :$ ! thaanks –  Maximilian1988 Apr 3 '13 at 0:19
2  
I have done things equally embarrassing more times than I can count. –  bob.sacamento Apr 3 '13 at 0:21

You have: $$ R - A X - B \cdot \frac{A X}{2 B} = R - A X - \frac{A B X}{2 B} = R - A X - \frac{A X}{2} = R - A X \left(1 + \frac{1}{2} \right) = R - \frac{3 A X}{2} $$

share|improve this answer
    
how did you edit it so it looks that good? –  Maximilian1988 Apr 3 '13 at 0:22
    
Look at the help for formatting, in particular here. You should be able to ask to edit your own post and look at how I wrote it. –  vonbrand Apr 3 '13 at 0:24
1  
ok sweet! Ill have a look at it –  Maximilian1988 Apr 3 '13 at 0:27
1  
Stupid braino. Thanks, fixed. –  vonbrand Apr 3 '13 at 0:31
1  
BTW, your final $X = \dfrac{2 R}{3 A}$. –  vonbrand Apr 3 '13 at 0:32

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.