lim [3-√(5+4x)]/(√x-1),x趋于1求极限

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lim [3-√(5+4x)]/(√x-1),x趋于1求极限
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lim [3-√(5+4x)]/(√x-1),x趋于1求极限
lim [3-√(5+4x)]/(√x-1),x趋于1
求极限

lim [3-√(5+4x)]/(√x-1),x趋于1求极限
lim [3-√(5+4x)]/(√x-1)
=lim (4-4x)/{(√x-1)【3+√(5+4x)】}
=lim 4(1-√x)(1+√x)/[6(√x-1)]
=-4/3

上下求导,就好了
不管是√(x-1)还是(√x)-1

1、x→+∞lim (4x^2-3x+1) &#47; (2x^2-6x+5)=lim (4x^2-3x+1)&#47;x^2 &#47; (2x^2-6x+5)&#47;x^2=lim (4-(3&#47;x)+(1&#47;x^2)) &#47; (2-(6&#47;x)+(5&#47;x^2))=(4-0+0) &#47; (2-0+0)=4&#47;2=2 2、x→+∞lim [(2x-1...

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1、x→+∞lim (4x^2-3x+1) &#47; (2x^2-6x+5)=lim (4x^2-3x+1)&#47;x^2 &#47; (2x^2-6x+5)&#47;x^2=lim (4-(3&#47;x)+(1&#47;x^2)) &#47; (2-(6&#47;x)+(5&#47;x^2))=(4-0+0) &#47; (2-0+0)=4&#47;2=2 2、x→+∞lim [(2x-1)&#47;(2x+1)]^(x+1)=lim [(2x+1-2)&#47;(2x+1)]^(x+1)=lim [1-2&#47;(2x+1)]^(x+1)=lim [1-2&#47;(2x+1)]^[2(x+1)&#47;2]=lim [1-2&#47;(2x+1)]^[(2x+1+1)&#47;2]=lim [1-2&#47;(2x+1)]^[(2x+1)&#47;2] * lim [1-2&#47;(2x+1)]^[1&#47;2]=lim [1-2&#47;(2x+1)]^[(2x+1)&#47;2] * 1=lim [1-2&#47;(2x+1)]^[(2x+1)&#47;-2 * -1]=[lim [1-2&#47;(2x+1)]^[(2x+1)&#47;-2]]^(-1)根据重要的极限:lim(x→∞) (1+1&#47;x)^x=e=e^(-1) 3、x→1lim sin(x-1) &#47; (x-1)换元:t=x-1=lim(t→0) sint &#47; t根据重要的极限:lim sinx&#47;x=1=1 有不懂欢迎追问

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