V. Limits an continuity of functions.
1. Evaluate limits:
x2 −9 x3 +8 2 −1 x3 −2x2 −4x+8
(a) limx→3 3 , (b) limx→−2 x2 −x−6
, (c) limx→1 xx5 −1 , (d) limx→2 x4 −8x2 +16
,
√ −27
x √ √3
2 +1−1
(e) limx→7 x−7 ,
x−6−1
(f) limx→0 1−√x2 +x+1 ,
x
(g) limx→0 √x2 +16−4 ,
x
(h) limx→0 x+1−1
x
,
tg x
(i) limx→π 1+cos
sin2 x
x
, (j) limx→0 2x−sin
x+sin x
x
, (k) limx→ π4 sin 2x
,
sin 5x sin 4x tg x
(l) limx→0 x , (m) limx→0 sin 5x , (n) limx→0 sin 2x ,
x4 +2x−1
(o) limx→0 arctg3x
2x
, (p) limx→−∞ −x3 +4x−1 , (q) limx→−∞ x3 −2x+4 x+2
.
2. Determine limits using continuity of functions at some point:
sin x
1−x tg x
(a) limx→0 2 x , (b) limx→+∞ arcsin 1+x , (c) limx→0 arctg x
,
(d) limx→4 log √x−4
x−2
, (e) limx→0 3x·ctgx
.
3. Determine asymptotes of functions given by:
√ √
(a) f (x) = 1−x
x
, (b) f (x) = x − 2 x, (c) f (x) = x2 − 3x + 2,
x3 +8 sin x − 12 x2 +2x
(d) f (x) = x2 −4
, (e) f (x) = x2
, (f) f (x) = e x , (g) f (x) = x+1
.
4. Check if the following functions are continuous:
x2 for x < 1, x2 + x − 2 for x < −2,
(a) f (x) = (b) f (x) =
3 − x for x 1, x2 + 5x + 6 for x −2,
2
|x −x−6| for x 6= −2, cos x−1 for x 6= 0,
(c) if (x) = x+2
(d) f (x) = |x|
5 for x = −2, 0 for x = 0.
5. Extend, if it is possible, a given function in such a way that the extended function is continuous on the
whole real line. If:
1
tg 3x tg x−sin x
(a) f (x) = 5x
, (b) g(x) = x3
, (c) h(x) = sin x · sin x1 , (d) p(x) = 2 x−1 .
6. What is a value of p ∈ R which the following function is continuous for? If:
sin 5x
for x 6= 0,
f (x) = sin 8x
2p + 1 for x = 0.
7. What are A, B ∈ R which the following function is continuous for? If:
−2 sin x for x ¬ − π2 ,
g(x) = A sin x + B for − π2 < x ¬ π2 ,
cos x for x π2 .