Question

Write an equation for the nth term of the arithmetic sequence.

Then find a50.

3, 9, 15, 21, . . .

an= 6n-3
a50= ?

Answer 1

6(n-1)+3
a50= 297

Of course, your formula would work as well..

Answer 2

an = 3 + 6 (n-1)

the 50th term is 297

Explanation:

We know that the formula used to find the nth term of a sequence is given by:

an = a₁ + d(n - 1)

where an is the nth term, a₁ is the first term and d is the common difference.

In this case a₁ = 3, d = 6 and n =50.

Therefore:

an = 3 + 6(49) = 3 + 294 = 297.