电大经济数学基础形成
性考核册答案
标准化管理处编码[BBX968T-XBB8968-NNJ668-MM9N]
电大经济数学基础形成性考核册及参考答案
(一)填空题
x?sinx?___________________.答案:0 x1.limx?0?x2?1,x?02.设f(x)??,在x?0处连续,则k?________.答案:1
?k,x?0?3.曲线y?x在(1,1)的切线方程是 .答案:y?11x? 224.设函数f(x?1)?x2?2x?5,则f?(x)?____________.答案:2x
ππ5.设f(x)?xsinx,则f??()?__________.答案:?
22(二)单项选择题
1. 函数y?x?1的连续区间是( D ) 2x?x?2A.(??,1)?(1,??) B.(??,?2)?(?2,??)
C.(??,?2)?(?2,1)?(1,??) D.(??,?2)?(?2,??)或(??,1)?(1,??)
2. 下列极限计算正确的是( B )
A.limxxx?0?1 B.lim?x?0xx?1
C.limxsinx?01sinx?1 D.lim?1
x??xx
3. 设y?lg2x,则dy?( B ).
11ln101dx B.dx C.dx D.dx 2xxln10xxA.
4. 若函数f (x)在点x0处可导,则( B )是错误的.
A.函数f (x)在点x0处有定义 B.limf(x)?A,但A?f(x0)
x?x0 C.函数f (x)在点x0处连续 D.函数f (x)在点x0处可微
5.当x?0时,下列变量是无穷小量的是( C ).
sinx C.ln(1?x) D.cosx xA.2x B.
(三)解答题
1.计算极限
x2?3x?21??(1)lim 2x?12x?1x2?5x?61? (2)lim2x?2x?6x?82原式=lim(x-2)(x-3)
x?2(x-2)(x-4)1?x?11??
x2(3)limx?0原式=lim(1?x?1)(1?x?1)
x?0x(1?x?1)
=limx?0?1
1?x?11 2 =?x2?3x?51? (4)lim2x??3x?2x?4335?2xx=1
原式=
3433??2xx1?(5)limsin3x3?
x?0sin5x5sin3x33原式=lim3x =
5x?0sin5x55xx2?4?4 (6)limx?2sin(x?2)原式=limx?2x?2
sin(x?2)x?2=
lim(x?2)x?2sin(x?2)limx?2x?2 = 4
1?xsin?b,x?0?x?2.设函数f(x)??a,x?0,
?sinxx?0?x?问:(1)当a,b为何值时,f(x)在x?0处有极限存在
(2)当a,b为何值时,f(x)在x?0处连续. 解:(1)lim?f(x)?b,x?0x?0?limf(x)?1
limf(x)?f(0)?1
x?0当 a?b?1时,有(2). 当a?b?1时,有limf(x)?f(0)?1
x?0 函数f(x)在x=0处连续.
3.计算下列函数的导数或微分:
(1)y?x2?2x?log2x?22,求y?
答案:y??2x?2xln2?ax?b,求y?
cx?d1
xln2(2)y?答案:y??a(cx?d)?c(ax?b)ad?bc?2(cx?d)(cx?d)2
(3)y?13x?5,求y?