Question

a theater has 50 seats in the front row. there are 4 additional seats in each row after that. how many seats are in the 20th row?​

Answer 1

126

Explanation:

The number of seats in each row can be expressed in the sequence

50, 54, 58, 62, ..... ,

This is an arithmetic sequence with n th term

`a_(n)` = a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Here a₁ = 50 and d = 4 , then

a₂₀ = 50 + (19 × 4) = 50 + 76 = 126

That is there are 126 seats in the 20th row