25 2. ln(1 +p
2)
3. 1 2014 4. 2p
3
5. a), c)
6.
1 3
2 7. 5
6 8. 1 p
3 3p
2⇡
9. 1 3
⇣5p 5 8⌘
10. 2e ⇡/2
11. Ä Ñ
Z x5 2x4+ 2x3 4x2+ 5x x4+ 2x2+ 1 dx =
Z
x 2 + 4x + 2 (x2+ 1)2dx t‰. Ï0⌧,
Z 4x
(x2+ 1)2dx =
Z 2· 2x
(x2+ 1)2dx = 2
x2+ 1 + C1
t‡
Z 2
(x2+ 1)2dx =
Z 2 sec2✓
(tan2✓ + 1)2d✓ (x = tan ✓ \ XX)
= Z
2 cos2✓d✓ = Z
1 + cos 2✓d✓
= ✓ +1
2sin 2✓ + C2 = ✓ + sin ✓ cos ✓ + C2
= arctan(x) + x
x2+ 1 + C2
t¿\,
Z x5 2x4+ 2x3 4x2+ 5x
x4+ 2x2+ 1 dx = 1
2x2 2x + arctan(x) + x 2 x2+ 1 + C
2
sin ✓ = 2u
1 + u2, cos ✓ = 1 u2
1 + u2, d✓ = 2 1 + u2du t‰.
✓ = ⇡
3| L, u = 1 p3t‡,
✓ = ⇡
2| L, u = 1t¿\
Z ⇡/2
⇡/3
1
3 + 2 sin ✓ cos ✓d✓ = Z 1
1/p 3
✓ 1
3 + 2· 2u 1 + u2
1 u2 1 + u2
◆ · 2 1 + u2du
= Z 1
1/p 3
2
4u2+ 4u + 2du = Z 1
1/p 3
2
(2u + 1)2+ 1du
= arctan(2u + 1) 1
1/p 3
= arctan(3) arctan
✓ 2 p3 + 1
◆
t‰.
13.
ln
✓1 + x 1 x
◆
= ln(1 + x) ln(1 x)
= X1 n=1
( 1)n 1 n xn+
X1 n=1
1 nxn
= X1 n=1
( 1)n 1+ 1
n xn
t¿\
an = 8>
><
>>
:
0 n@ ›⇠
2
n n@ @⇠
t‰.
0 ansin(n)
n 2
n2 t‡, X1 n=1
2
n2@ ⇠4X¿\, X1
n=1
ansin(n)
n @ ⇠4\‰. (DP ⇣ ï)
X1 a sin(n) X1 a sin(n)
14. (a)
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5
-2 -1.5 -1 -0.5 0 0.5 1
r=1
(b) 2 sin 2✓ = 1–⌧
1¨Ñt–⌧ P · t Ãòî P⇣X ✓î ⇡ 12, 5⇡
12t‰.
0|⌧, lXî ◆tî
A = 4
"Z 5⇡/12
⇡/12
1
2(2 sin 2✓)2d✓ 1 2
✓5⇡
12
⇡ 12
◆#
= 4
Z 5⇡/12
⇡/12
2 sin2(2✓)d✓ 2⇡
3
= 4
Z 5⇡/12
⇡/12
1 cos(4✓)d✓ 2⇡
3
= 4
✓5⇡
12
⇡ 12
◆
sin(4✓)5⇡/12
⇡/12
2⇡
3
= p 3 + 2⇡
3
t‰.
15. x0(t) = sin t + csc t, y0(t) = cos t t¿\
ds = p
x0(t)2+ y0(t)2dt
= p
sin2t 2 + csc2t + cos2t dt =p
csc2t 1dt
= | cot t|dt
t‰.
0|⌧, lXî · X 8tî
s =
Z ⇡/3
⇡/6
| cot t|dt
= ln| sin t| ⇡/3
⇡/6
= ln(p 3)