帮一下,谢谢。
先化简,再求值。x-2/(x²-1)除号(2x+2)/(x²+2x+1)+1/x-1,其中x=根号2+1....
先化简,再求值。
x-2/(x²-1) 除号 (2x+2)/(x²+2x+1) +1/x-1,其中x=根号2+1. 展开
x-2/(x²-1) 除号 (2x+2)/(x²+2x+1) +1/x-1,其中x=根号2+1. 展开
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2013-08-18 · 知道合伙人教育行家
wangcai3882
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解:
(x-2)/(x²-1)÷(2x+2)/(x²+2x+1)+1/(x-1)
=(x-2)/(x-1)(x+1)÷2(x+1)/(x+1)²+1/(x-1)
=(x-2)/(x-1)(x+1)*(x+1)/2+1/(x-1)
=(x-2)/2(x-1)+1/(x-1)
=[(x-2)+2]/2(x-1)
=x/2(x-1)
=(√2+1)/2(√2+1-1)
=(√2+1)/(2√2)
=(2+√2)/4
(x-2)/(x²-1)÷(2x+2)/(x²+2x+1)+1/(x-1)
=(x-2)/(x-1)(x+1)÷2(x+1)/(x+1)²+1/(x-1)
=(x-2)/(x-1)(x+1)*(x+1)/2+1/(x-1)
=(x-2)/2(x-1)+1/(x-1)
=[(x-2)+2]/2(x-1)
=x/2(x-1)
=(√2+1)/2(√2+1-1)
=(√2+1)/(2√2)
=(2+√2)/4
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