Please help me with solving this equation?

Question

kris2015 · Answer

$$R(r _{1}r _{2})=r _{1}r _{2}$$

kris2015 · Answer

solving for r2

kris2015 · Answer

I'm thinking this as the first step:

$$Rr _{1}*Rr _{2}=r _{1} r _{2}$$

kris2015 · Answer

Wait a minute... I think I messed up.

$$R(r _{1}-r _{2})=r _{1}r _{2}$$

thesmartone · Answer

psstt, the distributive property only applies when you're multiplying a number/variable to the sum or difference of two other numbers/variable

like

a(b + c) = ab + ac

when multiplying 3 numbers, remember the associative property of multiplication:
a(bc) = (ab)c

since when you're multiplying, it doesn't matter which order you multiply in
For example
3 * 2 * 5
3 * 2 is 6, and 6 * 5 is 30
2* 5 is 10 and 10* 3 is 30

we arrive at the same answer 

now to isolate $r_2$, we need to do something to both sides to get rid of $r_1$

what is $r_1$ doing to $r_2$
Multiplying? Dividing? Adding? Subtracting?

We'll need to do the opposite of that to both sides to get rid of it from one side :)

kris2015 · Answer

Multiplying? So I would need to divide the $$r _{1}$$ on both sides?

thesmartone · Answer

oh is the question actually:
$$R(r _{1}-r _{2})=r _{1}r _{2}$$
In that case, you can distribute it using the distributive formula

a(b - c) = ab - ac

thesmartone · Answer

yes, you would need to divide $r_1$ on both sides :)

kris2015 · Answer

$$Rr _{1} - Rr _{2}=r _{1}r _{2}$$

kris2015 · Answer

Then,

$$Rr _{1}=r _{1}r _{2}-Rr _{2}$$

kris2015 · Answer

+, not -

kris2015 · Answer

$$\frac{ Rr _{1} }{ R-r _{1}}=r _{2}$$

kris2015 · Answer

+, not -, sorry

kris2015 · Answer

Wait a minute.... I feel so dumb now. lol I think I figured it out. :)

thesmartone · Answer

if you change the - to a + that should be correct :)

kris2015 · Answer

Thank you for your guidance. :)

thesmartone · Answer

Anytime! :)