Re: 求極限
用的方法還是和你的一樣
lim (√(x^2 + αx + 1) - (x + 1) ) = c
x→∞
[√(x^2 + αx + 1)]^2 - (x + 1)^2
→ lim ----------------------------------- = c
x→∞ √(x^2 + αx + 1) + (x + 1)
(α - 2 ) x
→ lim ----------------------------- = c
x→∞ √(x^2 + αx + 1) + (x + 1)
α - 2
→ lim ------------------------------------- = c
x→∞ α 1 1
√ ( 1 + --- + --- ) + ( 1 + --- )
x x^2 x
α - 2
→ -------------- = c
√1 + 1
→ α = 2 ( c + 1 )
_________________#
希望有幫上忙 :D
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