F5 Maths

Common difference = 3x+2 - (x+5) = 2x - 3The gernal term T(n) = x+5 + (2x-3)(n-1)Let T(k) be 31x - 40 , x+5 + (2x-3)(k-1) = 31x - 40(2x-3)(k-1) = 30x - 45k - 1 = (30x - 45)/(2x - 3)k - 1 = 15k = 1616 terms

2010-09-22 18:40:57 補充：
可不可用中文問?唔明

2010-09-22 19:25:53 補充：
31x - 40 is the last term which is given by your question.

只要找出31x - 40 是第幾個 term (T(k)) ,就知有幾個 terms 。

k = 16 , 所以有 16 個 terms 。