Re: [微分] 極限
※ 引述《debdeb ()》之銘言：
: Find c so that
: x+2c
: lim ------ = 8
: x→-∞ x-c
: 麻煩指點一下謝謝！
let c=c(x)
1.if (x+2c)/(x-c) is 0/0 or ∞/∞ type
x+2c 1+2c'
lim ------ = lim -------
x→-∞ x-c x→-∞ 1-c'
if (1+2c')/(1-c') is 0/0 or ∞/∞ type
we have 2c"/-c"=-2≠8 (→←)
let (1+2c')/(1-c')=8
1+2c'=8-8c'
c(x)=(7/10)x + C
2.if (x+2c)/(x-c)=8
c(x)=(7/10)x which is included in answer c(x)=(7/10)x + C
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