Question

The sum of the first n terms of an ap is 5 n square by 2 + 3 n by 2 . Find the n term of the 20 term of this AP

Answer 1

Answer:

Sum of two terms = 5(4)/2 + 3(2)/2 = 10+3 = 13 . Second term = 13 - 4 = 9 . Common difference = 9 - 4 = 5 . 20 th term = a + ( 20 - 1 )d = a+19d = 4 + 19(5) = 99