Rational Equations using LCD, I'm stuck.

[Guest]

I'm stuck.

x-3...........3x
---- + 4 = ----
x-4............x


x(x-3)+4x(x-4)=3x(x-4)
x^2 - 3x + 4x^2 -16 = 3x^2 - 12x

2x^2 -3x = -12x
2x^2 + 9x = 0
x(2x + 9)= 0

And I'm stuck. I don't know if that is right or wrong, and if I did it right from there..then I don't know what to do. Help, please?

 

[opticaltempest]

x(x-3)+4x(x-4)=3x(x-4)
x^2 - 3x + 4x^2 -16 = 3x^2 - 12x
2x^2 -3x = -12x
2x^2 + 9x = 0
x(2x + 9)= 0

When you simplified line 1 you made a mistake.
See if you can spot it...

 

[Denis]

I'm stuck.

x-3...........3x
---- + 4 = ----
x-4............x

Make your life easier; start this way:
since 3x / x = 3, then
(x - 3) / (x - 4) + 4 = 3
(x - 3) / (x - 4) = -1

OK?