中一數學通項2題

2013-02-18 12:48 am
write down the nth term of the following sequence.搵通項
(A)2,6,12,20.......
(B) 2,24,108,320,......

回答 (2)

2013-02-18 10:37 am
✔ 最佳答案
write down the nth term of the following sequence.搵通項
(A)2,6,12,20.......
2=1*2 , 6 =2*3 12=3*4 20=4*5
2= 1*(1+1) 6=2*(2+1) 12=3*(3+1) 20=4*(4+1)
nth term=n*(n+1)
(B) 2,24,108,320,......
2=2 24=3*2^3 108 = 4*3^3 320 =5*4^3
2=(1+1)*1^3 24=(2+1)(2)^3 108=(3+1)(3^3) 320=(4+1)(4^3)
nth term=(n+1)(n^3)
參考: ME
2013-02-18 2:38 am
Hi i am marcoleongk89 , today I am going to help you solve the question

(A)2,6,12,20.......Ans = 2



(B) 2,24,108,320,...... Answer = 2

2013-02-19 00:24:09 補充:
A)2,6,12,20.......
2=1*2 , 6 =2*3 12=3*4 20=4*5
2= 1*(1+1) 6=2*(2+1) 12=3*(3+1) 20=4*(4+1)
nth term=n*(n+1)
(B) 2,24,108,320,......
2=2 24=3*2^3 108 = 4*3^3 320 =5*4^3
2=(1+1)*1^3 24=(2+1)(2)^3 108=(3+1)(3^3) 320=(4+1)(4^3)
nth term=(n+1)(n^3)
參考: , Herman


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