Question

求极限lim5的n次方-4的n-1次方／5的n+1次方+3的n+2次方,n趋向正无穷

Answer 1

lim (5^n-4^(n-1))/(5^(n+1)+3^(n+2))

分子分母同除以5^n

=lim (1-(1/5)(4/5)^(n-1))/(5+3^2(3/5)^n)

=(1-0)/(5+0)

=1/5

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