(1) If the 15th term of the sequence 3, 3+x, 3+2x, 3+3x, ... is 31, find the 34th term of the sequence.
(2) If the 21st ter一of the sequence 3x+7, 4x+7, 5x+7, 6x+7, ... s 122, find the 50th term of the sequence.
(3) If the 21st term of the sequence 5, 5+x, 5+2x, 5+3x, 5+4x, ... is 45, find the 51st term of the sequence.
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F.1 數學
2007-07-27 11:17 pm
回答 (3)
2007-07-27 11:26 pm
✔ 最佳答案
The Squence is 3+(n-1)xfrom the question,
3+(15-1)x = 31
x = 2
To the question, n is 34
so, 3+2(34-1) = 69
2007-07-27 15:34:21 補充：
The Sequence is (n+2)x+7From the question,(21+2)x+7 = 122 x = 5To the question, n is 50so, 5(50+2)+7 =267The Sequence is 5+(n-1)xFrom the question, 5+(21-1)x = 45 x = 2To the question, n is 51so, 5+2(51-1) = 105
參考: ME
2007-07-27 11:52 pm
The Squence is 3+(n-1)x
from the question,
3+(15-1)x = 31
x = 2
To the question, n is 34
so, 3+2(34-1) = 69
from the question,
3+(15-1)x = 31
x = 2
To the question, n is 34
so, 3+2(34-1) = 69
2007-07-27 11:29 pm
(1)
z=3+(y-1)x
if y=15, z=31
31=3+(15-1)x
x=(31-3)/14=28/14=2
so if y=34
z=3+(34-1)*2=69
(2)
z=7+(y+2)x
if y = 21 and z=122
122=7+(21+2)x
x=(122-7)/23=115/23=5
so if y=50
z=7+(50+2)*5=267
(3)
z=5+(y-1)x
if y=21 and z=45
45=5+(21-1)x
x=(45-5)/20=40/20=2
so if y=51
z=5+(51-1)*2=105
z=3+(y-1)x
if y=15, z=31
31=3+(15-1)x
x=(31-3)/14=28/14=2
so if y=34
z=3+(34-1)*2=69
(2)
z=7+(y+2)x
if y = 21 and z=122
122=7+(21+2)x
x=(122-7)/23=115/23=5
so if y=50
z=7+(50+2)*5=267
(3)
z=5+(y-1)x
if y=21 and z=45
45=5+(21-1)x
x=(45-5)/20=40/20=2
so if y=51
z=5+(51-1)*2=105
收錄日期: 2021-04-12 20:40:57
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