SOLUTION: I am trying to understand if the equation I have done is anywhere near correct. I think that I understand steps 1-4 correctly but the last two I do not which then makes my answer i

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: I am trying to understand if the equation I have done is anywhere near correct. I think that I understand steps 1-4 correctly but the last two I do not which then makes my answer i      Log On


   

Question 668261: I am trying to understand if the equation I have done is anywhere near correct. I think that I understand steps 1-4 correctly but the last two I do not which then makes my answer incorrect. I have two more problems to do like this one; if I cannot understand the first one then the rest will not be correct. Here is what I have so far.
Problem A: x2 – 2x – 13 = 0
Step 1: I need to move the constant term which is “13” to the right side too. As always we need to remember that what we do to one side we have to do to the other.
X2 – 2x – 13 = 0
X2 – 2x – 13 + 13 = 0 + 13
X2 – 2x + 0 = 0 + 13
X2 – 2x = 0 +13
X2 – 2x = 13
Step 2: Here I am going to multiply each term by four times the coefficient of the x term.
4 * 1 =
4x2 – 8 x = 52
Step 3: Square the coefficient of the original x term and add it to both sides of the equation. Throughout my equation I have learned that the x term is 2. However, for this step I need to square 2 and when I do that equals 4. I will add 4 to both sides of my equation like this.
4x2 – 8x + 4 = 52 + 4
4x2 – 8x + 4 + = 56
Step 4: Take the square roof of both sides.
(2x-2) * (2x-2) = 4x2 - 4x - 4x + 4
4x2 - 8x + 4 the expression on the left side of the equation
(2x - 22) = 56
2x - 2 = +/- sqrt(56)
Step 5: Set the left side of the equation equal to the positive square root of the number on the right side and solve for x. Once again remember what you do to one side you will have to do to the other.
2x - 2 = sqrt(56)
2x = sqrt(56) + 2
At this time I will need to divide both sides of the equation by 2 to and once I do it will look like this.
x = sqrt(56) + 2) / 2
Step 6: Set the left side of the equation equal to the negative square root of the number on the
right side of the equation and solve for x.
2x - 2 = - sqrt(56)
2x = - sqrt(56) + 2
divide both sides of the equation by 2 to get:
x = sqrt(56) + 2) / 2
Found 2 solutions by ReadingBoosters, MathTherapy:
Answer by ReadingBoosters(3246) About Me  (Show Source):
You can put this solution on YOUR website!
Starting where you ended
%282+%2B-+sqrt%2856%29%29%2F2
...
%282+%2B-+sqrt%284%2A2%2A7%29%29%2F2
%282+%2B-+2sqrt%2814%29%29%2F2
...
2%2F2+%2B-+cross%282%29sqrt%2814%29%2Fcross%282%29
1+%2B-+sqrt%2814%29
.....................
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Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

You seem to be attempting to solve the equation by COMPLETING THE SQUARE. If that's so, then why are you doing step 2? If I'm correct in what you're trying to do, who told you that you had to do step 2? I've never heard of this step when one attempts to solve a quadratic equation by COMPLETING THE SQUARE.

Step 2: Here I am going to multiply each term by four times the coefficient of the x term.

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