# SOLUTION: 12x^2 + 12x -9= 0 answer: x= -3/2 or 1/2 how did my text book get this answer i tought there was going to be a 4 involved because 4 .3 is 12

Algebra ->  Algebra  -> Quadratic Equations and Parabolas -> SOLUTION: 12x^2 + 12x -9= 0 answer: x= -3/2 or 1/2 how did my text book get this answer i tought there was going to be a 4 involved because 4 .3 is 12      Log On

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Question 183541: 12x^2 + 12x -9= 0

how did my text book get this answer i tought there was going to be a 4 involved because 4 .3 is 12

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12x^2 + 12x -9= 0
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Divide by 3

Factor it
(2x+3)*(2x-1) = 0
Either 2x+3 = 0, or 2x-1 = 0
2x+3 = 0
x = -3/2
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2x-1 = 0
x = 1/2
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 Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc) Quadratic equation (in our case ) has the following solutons: For these solutions to exist, the discriminant should not be a negative number. First, we need to compute the discriminant : . Discriminant d=64 is greater than zero. That means that there are two solutions: . Quadratic expression can be factored: Again, the answer is: 0.5, -1.5. Here's your graph:

NOTE: The solver gets the right answers, but the factors are not right.