Answers

2016-07-17T21:56:42+08:00
X^2-8x+7=0 x^2-8x=-7 x^2-8x+16=16-7 (x-4)^2=9 get the square root x-4=+-3 x=7 x=1 check: (7*7)-(8*7)=-7 42-49=-7 -7=-7 (7*1)-(8*1)=-7 7-8=-7 -1=-7 x=1 is a extraneous root
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