# math

posted by .

i solved by factoring like this:
3x^2+5x-12=0
(3x+4)(x-3)
-4 +3
x=-4 x=3

now i need to solve by the form x^2=k
How do I do that?

• math -

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 -

3x^2+5x-12=0
(3x-4)(x+3) = 0
so 3x-4 = 0 or x+3 = 0
x = 4/3 or x = -3

your version would give a middle term of -5x

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