Answers

2016-08-04T20:29:40+08:00
So, since (x+y)^2 = x^2+2xy+y^2, and x^2 has a numerical coefficient of 1, you just have to take away it's power, and you just have to look for the square root of 81. so \sqrt{x^2} =x, \sqrt{81} = 9. So you end up with: (x+9)^2. Sorry if this is confusing, but there you go.
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