SOLUTION: I am working on a quadratic equation. A=3, B=6, C=-4. I have worked the problem out to the point that x=-6 + sqrt 84. I reduced the problem to -6+2(sq rt 21) over 6. The text k

Algebra ->  Algebra  -> Quadratic Equations and Parabolas  -> Quadratic Equation Customizable Word Problems -> SOLUTION: I am working on a quadratic equation. A=3, B=6, C=-4. I have worked the problem out to the point that x=-6 + sqrt 84. I reduced the problem to -6+2(sq rt 21) over 6. The text k      Log On

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Question 438360: I am working on a quadratic equation. A=3, B=6, C=-4. I have worked the problem out to the point that x=-6 + sqrt 84. I reduced the problem to -6+2(sq rt 21) over 6. The text key says that it can be further reduced to -3+sqrt21 over 3, but I just cannot see how they get from my answer to theirs. Can you explain?
Answer by nerdybill(6948) About Me  (Show Source):
You can put this solution on YOUR website!
That's because instead of:
-6+2(sq rt 21) over 6
you should have:
-6+2(sq rt 21) over 12
.
Then, you can divide numerator and denominator by 2 to get:
-3+(sq rt 21) over 3
.
In the quadratic formula, the denominator is 'a' times 'c'