(x/x+1)-(x+3/x+1)*（2x平方+6 - 知识问答

(x/x+1)-(x+3/x+1)*（2x平方+6x/x平方+6x+9）其中x=2 要先把字母化简!

1个回答

x/(x+1)-[(x+3)/(x+1)]*(2x^2+6x)/(x^2+6x+9)
=x/(x+1)-[(x+3)/(x+1)]*[2x(x+3)]/(x+3)^2
=x/(x+1)-[(x+3)/(x+1)]*[2x/(x+3)]
=x/(x+1)-2x/(x+1)
=-x/(x+1)
=-2/(-2+1)
=2

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