SOLUTION: I have to complete the square: r^2+8r+72=0

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Question 278889: I have to complete the square: r^2+8r+72=0
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
r^2+8r+72=0
r^2+8r =-72
r^2+8r+16=-56 [(8/2)^2=16 completes the square. add it to each side.
r+4=+-sqrt(-56) square root of each side.
r+4=+-2sqrt(14)i
r=-4+2sqrt(14)i, r=-4-2sqrt(14)i
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Ed