Question

Find 26th term in the arithmetic sequence: -15,-35,-55,-75,...

Answer 1

-515

Explanation:

In this example the first value is −15 and every value afterwards is 20 less.After substituting these values to above formula, we obtain: All we have to do is add 25 twenties or 25 x 20 = 500 and -15 - 500 = -515

Answer 2

- 515

Explanation:

The n th term of an arithmetic sequence is

`a_(n)` = a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Here a₁ = - 15 and d = - 35 - (- 15) = - 35 + 15 = - 20, thus

`a_(26)` = - 15 + (25 × - 20) = - 15 - 500 = - 515