Question

NEED HELP FAST WILL GIVE BRAINLIEST

Answer 1

Answer:

(a) $a_n=15+3n$

(b) Row 35 has 120 seats

Step-by-step explanation:

Arithmetic sequences

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 $a_1=18$. 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):

$a_n=a_1+(n-1)r$

$a_n=18+(n-1)(3)=18+3n-3=15+3n$

(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