Chapter 12 Sequences; Induction; the Binomial Theorem
Chapter 12 Sequences; Induction; the Binomial Theorem
Chapter 12 Sequences; Induction; the Binomial Theorem
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<strong>Chapter</strong> <strong>12</strong> Review Exercises<br />
29.<br />
7<br />
∑<br />
k = 1<br />
10<br />
30. ∑ ( )<br />
k = 1<br />
⎛<br />
7<br />
⎞ ⎛<br />
7<br />
⎞<br />
⎛1⎞ ⎛1⎞<br />
k ⎜1−<br />
1<br />
1 1<br />
⎜ ⎟ ⎟ ⎜ −<br />
3 1<br />
⎜ ⎟ ⎟<br />
⎛ ⎞ ⎜ ⎝ ⎠ ⎟ ⎜ ⎝3⎠<br />
⎟<br />
⎜ ⎟ = =<br />
⎝3⎠ 3⎜ 1 ⎟ 3⎜ 2 ⎟<br />
1−<br />
⎛ ⎞<br />
⎜ 3 ⎟ ⎜ ⎜ ⎟<br />
3 ⎟<br />
⎝ ⎠ ⎝ ⎝ ⎠ ⎠<br />
1⎛<br />
1 ⎞<br />
= ⎜1−<br />
⎟<br />
2 ⎝ 2187 ⎠<br />
1 2186 1093<br />
= ⋅ = ≈0.49977<br />
2 2187 2187<br />
( )<br />
⎛<br />
10<br />
k 1− −2 ⎞<br />
⎛1−1024<br />
⎞<br />
− 2 = − 2⎜<br />
⎟=−2<br />
⎜<br />
⎜ ⎟<br />
1 −( −2) ⎟ 3<br />
⎝ ⎠<br />
⎝ ⎠<br />
2<br />
=− ( − 1023)<br />
= 682<br />
3<br />
31. Arithmetic<br />
a = 3, d = 4, a = a + ( n−<br />
1) d<br />
1 n 1<br />
a 9 = 3 + (9 − 1)4 = 3+ 8(4) = 3+ 32 = 35<br />
32. Arithmetic<br />
a = 1, d = − 2, a = a + ( n−1)<br />
d<br />
1 n 1<br />
a 8 = 1 + (8−1)( − 2) = 1+ 7( − 2) = 1− 14 = −13<br />
33. Geometric<br />
1<br />
n 1<br />
a1 = 1, r = , n = 11; an<br />
= a1r −<br />
10<br />
a<br />
11<br />
11−1 10<br />
⎛ 1 ⎞ ⎛ 1 ⎞<br />
= 1⋅ ⎜ ⎟ = ⎜ ⎟<br />
⎝ 10 ⎠ ⎝ 10 ⎠<br />
1<br />
=<br />
10,000,000,000<br />
34. Geometric<br />
n<br />
a = 1, r = 2, n= 11; a = a r −<br />
1 n 1<br />
11−1 10<br />
( ) ( )<br />
a 11 = 1⋅ 2 = 2 = 1024<br />
35. Arithmetic<br />
a = 2, d = 2, n = 9, a = a + ( n−<br />
1) d<br />
1 n 1<br />
a 9 = 2 + (9− 1) 2 = 2+<br />
8 2<br />
= 9 2 ≈<strong>12</strong>.7279<br />
36. Geometric<br />
n<br />
a = 2, r = 2, n= 9, a = a r −<br />
1 n 1<br />
−<br />
( ) ( )<br />
9 1 8<br />
a9 = 2 2 = 2 2 = 2⋅16<br />
= 16 2 ≈ 22.6274<br />
1<br />
1<br />
37. 7 1 20 1<br />
a = a + 6d = 31 a = a + 19d<br />
= 96;<br />
Solve <strong>the</strong> system of equations:<br />
a + 6d<br />
= 31<br />
1<br />
a1<br />
+ 19d<br />
= 96<br />
Subtract <strong>the</strong> second equation from <strong>the</strong> first<br />
equation and solve for d.<br />
− 13d<br />
=−65<br />
d = 5<br />
a 1 = 31− 6(5) = 31− 30 = 1<br />
a = a + n−<br />
d<br />
n<br />
( )<br />
( n )( )<br />
1 1<br />
= 1+ −1 5<br />
= 1+ 5n<br />
−5<br />
= 5n<br />
−4<br />
General formula: { a } = { 5n−<br />
4}<br />
38. 8 1 17 1<br />
n<br />
a = a + 7d =− 20 a = a + 16d<br />
= − 47;<br />
Solve <strong>the</strong> system of equations:<br />
a + 7d<br />
=−20<br />
1<br />
a1<br />
+ 16d<br />
=−47<br />
Subtract <strong>the</strong> second equation from <strong>the</strong> first<br />
equation and solve for d.<br />
− 9d<br />
= 27<br />
d = −3<br />
a 1 = −20 −7( − 3) = − 20 + 21 = 1<br />
a = a + n−<br />
d<br />
n<br />
( )<br />
( n )( )<br />
1 1<br />
= 1+ −1 −3<br />
= 1− 3n<br />
+ 3<br />
=− 3n<br />
+ 4<br />
General formula: { a } = { − 3n+<br />
4}<br />
39. 10 1 18 1<br />
a = a + 9d = 0 a = a + 17d<br />
= 8;<br />
Solve <strong>the</strong> system of equations:<br />
a + 9d<br />
= 0<br />
1<br />
a1<br />
+ 17d<br />
= 8<br />
Subtract <strong>the</strong> second equation from <strong>the</strong> first<br />
equation and solve for d.<br />
− 8d<br />
=−8<br />
d = 1<br />
a 1 = − 9(1) = − 9<br />
a = a + n−<br />
d<br />
n<br />
( )<br />
( n )( )<br />
1 1<br />
=− 9+ −1 1<br />
=− 9+ n −1<br />
= n −10<br />
General formula: { a } = { n−<br />
10}<br />
n<br />
n<br />
<strong>12</strong>75<br />
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