SOLUTION: how do you work 10r^2+20r-73=7 with completing the square?

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Question 616069: how do you work 10r^2+20r-73=7 with completing the square?
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
how do you work 10r^2+20r-73=7 with completing the square?
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10r^2+20r-73=7
add 73 to both sides:
10r^2+20r=80
divide both sides by 10:
r^2+2r = 8
add 1/2 'b', square it and add to both sides:
r^2+2r+1 = 8+1
(r+1)^2 = 9
take the square root of both sides:
r+1 = +- 3
r = -1 +- 3
r = {-4, 2}