anonymous one year ago Find x in this proportion. x|3 = x+2|5 (they are fractions. Please show answer and how you got it!)

1. anonymous

@Nnesha @e.mccormick @Donblue

2. e.mccormick

So x is to 3 as x+2 is to 5? Know how to set those up in fractional form?

3. zzr0ck3r

$$\frac{x}{3}=x+\frac{2}{5}$$ I think the easiest thing would be to multiply everything by the LCM of the denominators, which is 15 $$15\frac{x}{3}=15x+15\frac{2}{5}$$ $$5x=15x+6$$ Can you solve now?

4. e.mccormick

zz, I think they meant: $$\dfrac{x}{3} = \dfrac{x+2}{5}$$

5. zzr0ck3r

Was it $$\frac{x}{3}=\frac{x+2}{5}$$?

6. anonymous

x/3=x+ 2/5 or , 5x=15x+6 or, 15x+6=5x or,10x=6 or,x=6/10=3/5=0.6

7. anonymous

ye @e.mccormick and @Learner11 i tried that, thats wrong

8. zzr0ck3r

ahh, try the same thing with that! $\frac{x}{3}=\frac{x+2}{5}$ $15*\frac{x}{3}=15*\frac{x+2}{5}$ $5x=3(x+2)$ now solve for $$x$$?

9. anonymous

answer choices are -1 , 1 , 2, 3. :P i keep doin this wrong

10. e.mccormick

As a general rule: $$\dfrac{a}{b}=\dfrac{c}{d}$$ type proportions can alsways use cross multiplication to move forward. Cross multiplication basically does what xx did. He just multiplied hte bottoms (3 and 5) first. But if you don't multiply them out, then you can cancel quickly: $$\dfrac{a}{b}=\dfrac{c}{d}$$ $$\dfrac{a}{b}\times \dfrac{bd}{1}=\dfrac{c}{d}\times \dfrac{bd}{1}$$ $$\dfrac{a}{\cancel{b}}\times \dfrac{\cancel{b}d}{1}=\dfrac{c}{\cancel{d}}\times \dfrac{b\cancel{d}}{1}$$ $$\dfrac{a}{1}\times \dfrac{d}{1}=\dfrac{c}{1}\times \dfrac{b}{1}$$ $$a\times d=c\times b$$ $$ad=cb$$ That is a general way to start. Then solve for the unknown...

11. anonymous

thank you!

12. e.mccormick

What steps are you using when you solve the: 5x=3(x+2)