How would I work this problem out if I did not want to cross multiply?

$\displaystyle \frac{18-5x}{3x+2}=\frac{7}{3}$

I would think we should start with the LCD 3(3x+2) no?

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- Jul 9th 2009, 05:48 PMallyourbass2212Linear Equations, Fractions
How would I work this problem out if I did not want to cross multiply?

$\displaystyle \frac{18-5x}{3x+2}=\frac{7}{3}$

I would think we should start with the LCD 3(3x+2) no? - Jul 9th 2009, 06:14 PMKasper
- Jul 9th 2009, 06:34 PMShyam
- Jul 9th 2009, 06:47 PMKasper
Is this what your trying to do with the LCD?

$\displaystyle \frac{18-5x}{3x+2}=\frac{7}{3}$

$\displaystyle \frac{18-5x}{3x+2}-\frac{7}{3}=0$

$\displaystyle

\frac{3(18-5x)-7(3x+2)}{3(3x+2)}=0

$

Because this still gives you

$\displaystyle 3(18-5x)-7(3x+2)=0$

Which is the same as cross multiplying and dividing which gives

$\displaystyle

3(18-5x)=7(3x+2)

$

So you*could*do it that way, but it's much more work.