Question

Calculate the number of terms in the following arithmetic sequence. 6;1;-4;-9....... -239​

Answer 1

50

Explanation:

Given

first term (a) = 6

Common Difference (d) = 1 - 6 = - 5

Last term (tn )= - 239

Number of terms (n) = ?

We know

Tn = a + ( n - 1 ) d

- 239 = 6 + (n - 1) (-5)

- 239 = 6 - 5n + 5

- 239 = 11 - 5n

5n = 11 + 239

5n = 250

n = 250 / 5

n = 50

The number of terms is 50.