SOLUTION: x^2 - 12x =45 x^2 -12x +36=81 (need to know how my text book got +36 and 81) (x-6)^2 =81 x-6= +-9 x= +-9 +6 x=15 or -3

Question 184090: x^2 - 12x =45
x^2 -12x +36=81 (need to know how my text book got +36 and 81)
(x-6)^2 =81
x-6= +-9
x= +-9 +6
x=15 or -3
Found 2 solutions by Earlsdon, jim_thompson5910:
Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
I really can't anwer the question you raised but your solution is the correct one!
Remember, book-answers are not infallible!
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Start with the given equation

What the book is doing is completing the square on the left side (which will help isolate "x").

Take half of the "x" coefficient -12 to get -6. Square -6 to get 36. Add this value to both sides.

Combine like terms.

Factor the left side

Take the square root of both sides.

or Break up the "plus/minus"

or Take the square root of 81 to get 9

or Add 6 to both sides.

or Combine like terms.

So the solutions are or
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