SOLUTION: The first term of an Ap is 11 while the last term is 144. If the common difference is 7 find the number of term it has

Algebra ->  Sequences-and-series -> SOLUTION: The first term of an Ap is 11 while the last term is 144. If the common difference is 7 find the number of term it has      Log On


   

Question 793760: The first term of an Ap is 11 while the last term is 144. If the common difference is 7 find the number of term it has
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
a=11
d=7
tn = 144
tn=a+(n-1)d
144=11+(n-1)*7
144=11+7n-7
144-11+7=7n
140=7n
n= 140/7
n=20