Cinema auditorium is built for 3300 people. The first row is planned for 36 seats and each next gradually 4 more. How many rows of seats will have auditorium?

Correct answer:

n =  33

Step-by-step explanation:

3300=n2(a1+an)=n2(a1+a1+d(n1)) 3300=n2(a1+a1+d(n1)) 3300=36n+n/2(n1)4  3300=36 n+n/2 (n1) 4 2n234n+3300=0 2n2+34n3300=0  a=2;b=34;c=3300 D=b24ac=34242(3300)=27556 D>0  n1,2=b±D2a=34±275564 n1,2=34±1664 n1,2=8.5±41.5 n1=33 n2=50   Factored form of the equation:  2(n33)(n+50)=0 n>0 n=n1=33=33

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