SOLUTION: Hello, In the proof of the quadractic equation, you begin by dividing both parts by "a". ax2 (2 is the square)+ bx + c = 0 (divide both sides by a) x2(2 is the square

Question 111186: Hello,
In the proof of the quadractic equation, you begin by dividing both parts by "a".
ax2 (2 is the square)+ bx + c = 0
(divide both sides by a)
x2(2 is the square) + b/a.x + c/a = 0
(then suddenly)
x2(2 is the square) 2.(b/2.a).x = c/a = 0
Then all of a sudden, a "2" appears. Where did that come from?
Thank you for your help.
Barbara
Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
Deriving the quadratic formula:
Divide by a.
Subtract c/a from both sides.
Now complete the square in x on the left side by adding the square of half the x-coefficient () to both sides.
Factor the left side.
Take the square root of both sides. You'll have two answers here, + and -
Simplify the contents of the radical.
Combine the fractions under the radical over a common denominator ()
Take the square root of the denominator.
Subtract from both sides.
Simplify the right side.

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