need help solving (X - 5)/6 = (X + 4)/2

misschristine_b

New member
Joined
Sep 29, 2007
Messages
2
I'm cannot seem to understand how to do this problem, can anyone explain it to me?

(X - 5) / 6 = (X + 4) / 2
 

jwpaine

Full Member
Joined
Mar 10, 2007
Messages
723
Re: NEED HELP

misschristine_b said:
I'm cannot seem to understand how to do this problem, can anyone explain it to me?

X - 5 X + 4
----- = -------
6 2[/list]
\(\displaystyle \L \frac{x - 5}{6} = \frac{x + 4}{2}\)

Cross multiply:

\(\displaystyle \L 2(x - 5) = 6(x + 4)\)

Solve for x..
John
 

misschristine_b

New member
Joined
Sep 29, 2007
Messages
2
Thank you so much, we haven't got to that part in our class but it's part of our homework.
 

soroban

Elite Member
Joined
Jan 28, 2005
Messages
5,588
Re: NEED HELP

Hello, Christine!

\(\displaystyle \L\frac{x\,-\,5}{6} \:=\:\frac{x\,+\,4}{2}\)

Maybe you didn't know about cross-multiplying,
. . but you do know how to do this . . .

Multiply both sides by 6: \(\displaystyle \L\:6\.\cdot\frac{x\,-\,5}{6}\;=\;6\,\cdot\,\frac{x\,+\,4}{2}\)

. . and we get: \(\displaystyle \L\:x\,-\,5 \;= \;3(x\,+\,4)\)

I trust you can finish it now . . .


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Here's another approach (not usually recommended) . . .

We have: \(\displaystyle \L\:\frac{x\,-\,5}{6}\;=\;\frac{x\,+\,4}{2}\)

Then: \(\displaystyle \L\:\frac{x}{6}\,-\,\frac{5}{6}\;=\;\frac{x}{2}\,+\,\frac{4}{2}\)

Subtract \(\displaystyle \frac{x}{2}\) from both sides: \(\displaystyle \L\;\frac{x}{6}\,-\,\frac{x}{2}\,-\,\frac{5}{6}\;=\;2\)
. . and we have: \(\displaystyle \L\:-\frac{x}{3}\,-\,\frac{5}{6}\;=\;2\)

Add \(\displaystyle \frac{5}{6}\) to both sides: \(\displaystyle \L\;-\frac{x}{3}\;=\;2\,+\,\frac{5}{6}\)
. . and we have: \(\displaystyle \L\:-\frac{x}{3}\;=\;\frac{17}{6}\)

Multiply both sides by -\(\displaystyle 3:\;\;\L-3\left(-\frac{x}{3}\right) \;=\;-3\left(\frac{17}{6}\right)\)

. . Therefore: \(\displaystyle \L\:x\;=\;-\frac{17}{2}\)

 
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