已知XY-2的绝对值与Y-1的绝对值互为相反数,试求代数式的值
xy分之二+(x+1)(y+1)分之二+(x+2)(y+2)分之二+……(x+2012)(y+2012)分之二
通俗易懂些)
人气:476 ℃ 时间:2020-03-27 10:35:54
解答
∵│xy-2│+│y-1│=0.
∴y-1=0,即y=1;
xy-2=0,x*1-2=0,x=2.
则2/xy+2/(x+1)(y+1)+2/(x+2)(y+2)+…+2/(x+2012)(y+2012)
=2/(1x2)+2/(2x3)+2/(3x4)+…+2/(2013x2014)
=2x[1/(1x2)+1/(2x3)+1/(3x4)+…+1/(2013x2014)]
=2x(1-1/2+1/2-1/3+1/3-1/4+…+1/2013-1/2014)
=2x(1-1/2014)
=2013/1007
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