# Math Help - Solving

1. ## Solving

I need to solve this for b

Here's what I got so far:

a(a-b) = 3s(3s+b)

a^2 - ab = 9s^2 + 3sb

divide it all by a

a^2/ a - ab/a = 9s^2/a + 3sb/a

gives

a - b = 9s^s/a + 3sb/a

-b = 9s^s/a + 3sb/a -a

....not sure what to do about that b in 3sb?

Thanks

I need to solve this for b

Here's what I got so far:

a(a-b) = 3s(3s+b)

a^2 - ab = 9s^2 + 3sb
Keep it up to this point.

Now get all the b terms on one side and everything else on the other:
$-ab - 3sb = 9s^2 - a^2$

Note the the LHS factors:
$b(-a - 3s) = 9s^2 - a^2$

You take it from here.

-Dan

3. The idea is to isolate b alone by itself in the lefthand side.

After your second line, collect all the b-terms at the lefthand side, factor out the b, etc,

Umm, let me continue...

a(a-b) = 3s(3s+b)

a^2 - ab = 9s^2 + 3sb

-ab -3sb = 9s^2 -a^2
b(-a -3s) = 9s^2 -a^2
b(-(3s +a)) = (3s +a)(3s -a)
Divide both sides by -(3s +a),
b = -(3s -a)