SOLUTION: {{{ (2r-5)^2=81 }}}

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Question 668176: +%282r-5%29%5E2=81+
Found 2 solutions by ReadingBoosters, MathTherapy:
Answer by ReadingBoosters(3246) About Me  (Show Source):
You can put this solution on YOUR website!
Starting with
%282r-5%29%5E2+=+81
...
(2r-5)(2r-5) = 81
...
4r%5E2+-+10r+-+10r+%2B+25+=+81
...
4r%5E2+-+20r+-+56+=+0
(4r+8)(r-7) = 0
4r+8 = 0, so r = highlight_green%28-8%2F4+=+-2%29
r-7 = 0, so r = highlight_green%287%29
...
Solutions
-2 and 7
............
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-Reading Boosters
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Answer by MathTherapy(10551) About Me  (Show Source):
You can put this solution on YOUR website!
+%282r-5%29%5E2=81+

sqrt%28%282r+-+5%29%5E2%29+=+_%2B-+sqrt%2881%29 ----- Taking square root of both sides

2r+-+5+=+_%2B-+9

2r - 5 = 9_____2r = 14______r = 14%2F2, or highlight_green%287%29

2r - 5 = - 9_____2r = - 4______r = %28-+4%29%2F2, or highlight_green%28-+2%29

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