NEED HELP FAST WILL GIVE BRAINLIEST
1. In a music stadium, there are 18 seats in the first row and 21 seats in the second row. The number of seats in a row continues to increase by 3 with each additional row.
(a) Write an explicit rule to model the sequence formed by the number of seats in each row. Show your work.
(b) Use the rule to determine which row has 120 seats. Show your work.

The question describes a situation where we must use arithmetic sequences. The first row of the music stadium has 18 seats. In terms of sequences, it means [tex]a_1=18[/tex]. Then we know each additional row has 3 more seats than the previous one. It gives us the common difference r=3.

(a) The expression for the n-th row will be given for the general term of an arithmetic sequence as follows (n>=1):

[tex]a_n=a_1+(n-1)r[/tex]

[tex]a_n=18+(n-1)(3)=18+3n-3=15+3n[/tex]

(b) If we know the row n has 120 seats:

120=15+3n

120-15=3n

105=3n

n=105/3=35

The row 35 will have 120 seats