# Simplify to quadratic form

1. Apr 16, 2008

### alpha01

can someone show how to simplify $$\frac{12x+9}{x} = x+9$$ so that it is in the quadratic form: x^2 -3x -9 = 0

multiplying both sides by x, subtracting both sides by 9 etc. . doesnt give me the quadratic.

2. Apr 16, 2008

### tiny-tim

Hi alpha01!

erm … I think you put 9 on the right-hand side instead of 9x.

3. Apr 16, 2008

### mubashirmansoor

Just multiply both sides by 'x' :

( x (12x + 9 ) ) / x = x ( x + 9 )

multiplied x on the left hand side cancels out with its denominator & by expanding the right hand side you will get;

12x + 9 = x^2 + 9x

Subtracting both sides by (12x + 9);

0 = x^2 +9x - 12x - 9

which means;

x^2 - 3x - 9 = 0

& thats what you are looking for...

4. Apr 16, 2008

### alpha01

thanks

5. Apr 17, 2008

### mubashirmansoor

Your welcome !!! :)

6. Apr 17, 2008

### ice109

how would he get a quadratic then

7. Apr 17, 2008

### ice109

sorry misread and now i can't delete