若lim(an)=a,则lim|an|=|a|反之是否成立?
举一反三
- 【单选题】若 f ( x ) = ( x − 1 ) x 2 − 1 2 , g ( x ) = x − 1 x + 1 ,则? A. f ( x ) = g ( x ) "> f ( x ) = g ( x ) B. lim x → 1 f ( x ) = g ( x ) "> lim x → 1 f ( x ) = g ( x ) C. lim x → 1 f ( x ) = lim x → 1 g ( x ) "> lim x → 1 f ( x ) = lim x → 1 g ( x ) D. 以上等式均不成立
- 5．关于函数极限，给出以下结论：① 若$\underset{x\to 0}{\mathop{\lim }}\,f({{x}^{2}})=A$，则$\underset{x\to 0}{\mathop{\lim }}\,f(x)=A$；② 若$\underset{x\to 0}{\mathop{\lim }}\,f({{x}^{3}})=A$，则$\underset{x\to 0}{\mathop{\lim }}\,f(x)=A$；③ 若$f(x)$是周期函数，且$\underset{x\to 0}{\mathop{\lim }}\,f(x)=A$，则$f(x)\equiv A$；④ 若$f(x)$是周期函数，且$\underset{x\to \infty }{\mathop{\lim }}\,f(x)=A$，则$f(x)\equiv A$。其中正确结论的编号是 A: ① ② B: ③ ④ C: ① ③ D: ② ④
- 请问lim(x->0+)lim(x->0-)lim(x->1+)lim(x->1-)
- 零件的工作应力σca、极限应力σlim、许用应力[σ]，则安全系数S为 A: σlim/[σ] B: σlim/σca C: σca/[σ] D: σca/σlim
- 若函数f(z)在z_0不连续，则: (lim)┬(z→z_0 ) [f(z)-f(z_0)]=0|(lim)┬(z→z_0 ) [f(z)-f(z_0)]≠0|(lim)┬(z→z_0 ) f(z)=f(z_0)|(lim)┬(Δz→0) f(z_0+Δz)=f(z_0)