Posted by keith on .
i solved by factoring like this:
3x^2+5x12=0
(3x+4)(x3)
4 +3
x=4 x=3
now i need to solve by the form x^2=k
How do I do that?

math 
helper,
3x^2 + 5x  12 = 0
This cannot be factored
This can be solved by completing the square or using the quadratic formula.
(3x + 4)(x  3) = 3x^2  5x  12
Does not equal 3x^2 + 5x  12 
math 
Reiny,
just switch your signs
3x^2+5x12=0
(3x4)(x+3) = 0
so 3x4 = 0 or x+3 = 0
x = 4/3 or x = 3
your version would give a middle term of 5x