SOLUTION: 4rē-28r=-49. Solve by completing the square

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Question 651875: 4rē-28r=-49. Solve by completing the square
Answer by Edwin McCravy(20064) About Me  (Show Source):
You can put this solution on YOUR website!
4rē-28r = -49

Divide through by the coefficient of rē which is 4:

4%2F4rē - 28%2F4r = -49%2F4

  rē - 7r = -49%2F4

To the side 

1.  Multiply the coefficient of r, which is -7, by 1%2F2,
getting -7%2F2
2.  Square that result:  %28-7%2F2%29%5E2 = 49%2F4
3.  Add that number to both sides of the equation:

  rē - 7r + 49%2F4 = -49%2F4 + 49%2F4

Factor the left side, combine the terms on the right

 (r - 7%2F2)(r - 7%2F2) = 0

Use the zero-factor property:

   r - 7%2F2 = 0;  r - 7%2F2 = 0

      r = 7%2F2;  r = 7%2F2

Both are the same, so

7%2F2 is a double solution or "a root of multiplicity 2".

Edwin