Steps are necessary.
1. If x + 1, 3x - 2 and 2x + 4 are three consecutive terms of an arithmetic sequence, find the value of x.
2. How many numbers with two digits are divisble by 6?
Some urgent questions
2008-09-05 1:33 am
回答 (3)
2008-09-09 1:58 am
✔ 最佳答案
1. If x+1, 3x-2 and 2x+4 are three consecutive terms of an arithmetic sequence, then the sum of the first and the third number will be 2 times of the second number.This means :
(x+1) + (2x+4) = 2(3x-2)
3x+5 = 6x-4
9 = 3x
x = 3
2. Total 15 numbers :
12,18,24,30,36,42,48,54,60,66,72,78,84,90,96
2008-09-09 2:00 am
應該是
[(x 1) (2x 4)]/2 = 3x - 2
因為他們是連續數的關係
最細和最大加起來除2就會等於中間那個了
你可以隨意想三個連續數來證明的
另一個方法是
Let y be the difference between the numbers
x + 1+y=3x-2 <--最細那個加上y的差別等於中間那個
3x-2 +y = 2x +4 <--中間那個加上y的差別等於最大那個
然後再求x了
答案都應該相同的
[(x 1) (2x 4)]/2 = 3x - 2
因為他們是連續數的關係
最細和最大加起來除2就會等於中間那個了
你可以隨意想三個連續數來證明的
另一個方法是
Let y be the difference between the numbers
x + 1+y=3x-2 <--最細那個加上y的差別等於中間那個
3x-2 +y = 2x +4 <--中間那個加上y的差別等於最大那個
然後再求x了
答案都應該相同的
2008-09-05 1:45 am
1. [(x + 1)+(2x + 4)]/c = 3x - 2
x=3 (4, 7, 10)
2. 15 (12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78, 84. 90. 96)
x=3 (4, 7, 10)
2. 15 (12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78, 84. 90. 96)
參考: myself
收錄日期: 2021-04-13 16:02:18
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