Question

If the nth term of the sequence -1 , 4, 9, 14..... Is 129. Then find the value of n. ​

Answer 1

27

Explanation:

129-(-1) = 130

130/5 = 26

26+1 = 27

Answer 2

n = 27

Explanation:

This is Arithmetic sequence

a = -1

Common difference = 4 - (-1) = 4 +1 = 5

an = a + (n-1)d

129 = -1 + (n-1)*5

129 + 1 = (n-1)*5

130 = (n-1)*5

130/5 = n - 1

26 = n - 1

n = 26 + 1

n =27