I'm stuck on a problem

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mallorymal

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Feb 9, 2008
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27
3x^2 + 4x = 4x^2 - 12

I ended up with the equation -x^2 + 4x + 12
Now, to find x should I factor it out or use the quadratic formula? I've been trying to factor it out but I can't seem to get it.
 
What you ended up with is not an equation. You lost an equal sign. What you have is an expression and has no "solution" unless you know the value(s) of x.
If you find your equal sign and end up with an equation whose 1st term has a negative coefficient, try multiplying both sides of your equation by "-1" and go from there.
 
3x^2 + 4x = 4x^2 - 12

I ended up with the equation -x^2 + 4x + 12 = 0
Now, to find x should I factor it out or use the quadratic formula? I've been trying to factor it out but I can't seem to get it.
Click to expand...

To add to Loren's advice:

I also suggest you multiply both sides of the equation by –1 before you factor:

-x^2 + 4x + 12 = 0
x^2 – 4x – 12 = 0

And yes, this can be factored. The pairs of integer factors of 12 are 1,12; 2,6; and 3,4. Can you figure it out from here? (Note: the quadratic formula will always work, even for equations that don’t factor “nicely.”)

Hope that helps.
 
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