感激不尽啊!数列t1,t2,t3,...,tn,中,t1=23,n>1时,tn=tn-1-3,当n为何值得时候是的tn=-4?_数学解答

感激不尽啊!
数列t1,t2,t3,...,tn,中,t1=23,n>1时,tn=tn-1-3,当n为何值得时候是的tn=-4?

人气：166 ℃　时间：2020-04-06 06:18:01

解答

tn=t(n-1)-3
tn-t(n-1) =-3
tn - t1 = -3(n-1)
tn = 26-3n
tn =-4
26-3n=-4
3n=30
n=10