Question 80102
:
 can someone please help me solve this rational equation b+3/b+b+4/b+5=15/Bsquared+5b
:
The way it's written is ambiguous, a few brackets would help alot
I assume you mean:
:
{{{((b+3)/b) + ((b+4)/(b+5))}}} = {{{15/(b^2+5b)}}}
:
Factor out b in the last denominator:
{{{((b+3)/b) + ((b+4)/(b+5))}}} = {{{15/(b(b+5))}}}
:
It becomes obvious that the common denominator is b(b+5), mult each term by that, then you have:
:
(b+5)(b+3) + b(b+4) = 15
(:
b^2 + 8b + 15) + (b^2 + 4b) = 15; FOIL and mult what's inside the brackets
:
b^2 + b^2 + 8b + 4b + 15 - 15 = 0; group like terms on the left
:
2b^2 + 12b = 0
:
2b(b + 6) = 0; factor out 2b
:
two solutions:
b = 0; cannot be a solution (0 in the denominator)
and 
b = -6
:
:
Check b = -6 in the original equation
{{{((-6+3)/-6) + ((-6+4)/(-6+5))}}} = {{{15/(-6^2+5(-6))}}}
:
I'll let you do the math here, and see that equality reigns.