Solving Quadratic Equation Using Box Factoring

[nordqvist11]

Homework Statement

f(x)=6x^2+9x-6

Where does this function intersect the x-axis (i.e. what are the roots or zeroes of f(x))?

Solve by factoring using the Box Method. When I use the method that is shown on this website http://www.purplemath.com/modules/factquad2.htm for this particular problem I end up with this as my factored down version of the equation.
(6x-3)(3x+6)
But that is wrong because I would end up with 18x^2 as my leading term instead of the 6x^2 (which is in the desired equation) when I FOIL them out.

My question is that does using the method on that website to factor down a quadratic work for this equation? If so, could someone tell me what I'm doing wrong.

Thanks :)

Homework Equations

The Attempt at a Solution

[PLAIN]http://5img.com/img836/4599/69quadproblem.jpg

 

[I like Serena]

Welcome to PF, nordqvist11!

Your equation looks like the last example on the page you mentioned.
It says there that you should take out the common factor first...

 

[nordqvist11]

You're right it does :). Thanks a lot, I got a real headache because of that.