SOLUTION: The forth term of an ap is 96.while the 25th term is 173.find the:(a)19thterm (b)the sum of 13th and 56th terms. Please help me to solve this equation.

Algebra ->  Sequences-and-series -> SOLUTION: The forth term of an ap is 96.while the 25th term is 173.find the:(a)19thterm (b)the sum of 13th and 56th terms. Please help me to solve this equation.      Log On


   



Question 1156657: The forth term of an ap is 96.while the 25th term is 173.find the:(a)19thterm (b)the sum of 13th and 56th terms. Please help me to solve this equation.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
The forth term of an ap is 96.
nth term of AP is t(n) = a+(n-1)&d
t(5) = a+4d
a+3d =96...……………..(1)

while the 25th term is 173
t(25) = a+24d
a+24d =173...……………..(2)
solve (1) & (2)
a+3d =96
a+24d =173 subtract (1) from (2)
21d = 77
d= 77/21
d=11/3
plug d in (1)
a+3d =96
a+ 3*(11/3)= 96
a=85
19th term is a+18d ( plug a & d) = 151
you continue
Find 13th.=a+12d,
56th. term a+55d
Add them up