Question

The front row of an auditorium has 10 seats. There are 50 rows in total. If each row has 2 more seats than the row before it, which expression gives the total

number of seats in the last row?

A) 10 + 2(50 - 1)
A 10+ 2(50)
C) 50(10 + 2)
D) 10 + 2^50

Answer 1

10 + 2 (50-1)

Explanation:

Because this is an arithmatic sequence (sequence where the same number is added over and over) you would use the formula

(first number in sequence) + (number in sequence -1) * the difference in between each number in the sequence)

Answer 2

10+2(50-1)

Explanation:

This is an arithmetic sequence

We know the first term a1 = 10

The common difference, d = 2

an = a1+d(n-1)

We want to find the number of terms when n = 50

a50 = 10+2(50-1)