微積分題目

2013-11-02 5:14 am
x-2
Lim ───────
x→-1 x2+4x-3


2x+4
Lim ───────
x→2 x-7


x3+3x2-10x
Lim ───────
x→2 x-2

2 - √x+4
Lim ───────
x→0 x


1 3
Lim ( ──── - ──── )
x→1 x-1 x3-1


2x+1
Lim ─────
x→∞ x2-x+1


Lim √x2-2x+10
x→∞


4-√x+15
Lim ─────
x→1 x2-1



我有打根號的都是包含整串數字喔!!例如第4題是根號裡面的x+4不是根號x加4喔!!!
還有例如第一題的X2這種就是X的平方,第三題的3X2就是3X的平方以此類推!!!



麻煩寫過程給我,越詳細越好,謝謝!!!!
更新1:

不好意思倒數第二題我打錯了 應該是Lim √x2-2x+10 x→-∞ 然後我這題作法還是有點不懂可以說明一下嗎謝謝 ---------------------------------------------- 最後一題 為什麼16-X-15下一步驟變成X-1不是1-X嗎?

回答 (2)

2013-11-02 7:38 am
✔ 最佳答案
lim(x->-1)_(x-2)/(x^2+4x-3)
=(-1-2)/(1-4-3)
=1/2

lim(x->2)_(2x+4)/(x-7)
=(4+4)/(2-7)
=-8/5

lim(x->2)_(x^3+3x^2-10x)/(x-2)
=lim(x->2)_(x^2+5)
=9

lim(x->0)_[2-√(x+4)]/x
=lim(x->0)_[2-√(x+4)]*[2+√(x+4)]/{x[2+√(x+4)]}
=lim(x->0)_-x/{x[2+√(x+4)]}
=lim(x->0)_-1/[2+√(x+4)]
=-1/(2+2)
=-1/4

lim(x->1)_[1/(x-1)-3/(x^3-1)]
=lim(x->1)_(x^2+x+1-3)/(x^3-1)
=lim(x->1)_(x^2+x-2)/(x^3-1)
=lim(x->1)_(x+2)/(x^2+x+1)
=3/4

lim(x->∞)_(2x+1)/(x^2-x+1)
=lim(x->∞)_(2x/x^2+1/x^2)/(1-x/x^2+1/x^2)
=0

lim(x->∞)_√(x^2-2x+10)
=lim(x->∞)_√(x^2-2x+1)
=lim(x->∞)_(x-1)
=∞

lim(x->1)_[4-√(x+15)]/(x^2-1)
=lim(x->1)_[4-√(x+15)]*[4+√(x+15)]/{(x^2-1)*[4+√(x+15)]}
=lim(x->1)_(16-x-15)/{(x^2-1)*[4+√(x+15)]}
=-lim(x->1)_(x-1)/{(x^2-1)*[4+√(x+15)]}
=-lim(x->1)_1/{(x+1)*[4+√(x+15)]}
=-1/[2*(4+4)]
=-1/16




2013-11-02 17:00:41 補充:
lim(x->2)_(x^3+3x^2-10x)/(x-2)
=lim(x->2)_(x^2+5x)
=14

lim(x->1)_[1/(x-1)-3/(x^3-1)]
=lim(x->1)_(x^2+x+1-3)/(x^3-1)
=lim(x->1)_(x^2+x-2)/(x^3-1)
=lim(x->1)_(x+2)/(x^2+x+1)
=3/3
=1
2013-11-02 11:18 am
知識長筆誤:


lim(x->2)_(x^3+3x^2-10x)/(x-2)
=lim(x->2)_(x^2+5x)
=14

lim(x->1)_[1/(x-1)-3/(x^3-1)]
=lim(x->1)_(x^2+x+1-3)/(x^3-1)
=lim(x->1)_(x^2+x-2)/(x^3-1)
=lim(x->1)_(x+2)/(x^2+x+1)
=1


收錄日期: 2021-04-30 18:08:59
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20131101000016KK05330

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