In the seating for a concert, the first row has 10 chairs. Every row after that has 2 more chairs. 7. What is the explicit formula that models this situation? 8. How many chairs are in row 20?

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  7. c(n) = 10 +2(n -1)

  8. c(20) = 48

Step-by-step explanation:

7. Your arithmetic sequence has first term a1=10 and constant difference d=2. The explicit formula for terms of an arithmetic sequence is ...

  an = a1 +d(n -1)

If we use c(n) as the function name for the function giving the number of chairs in row n, then we can fill in the numbers we know to get ...

  c(n) = 10 + 2(n -1)

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8. Evaluating the function when n=20, we find ...

  c(20) = 10 +2(10-1) = 10 +2·19 = 10 +38

  c(20) = 48

There are 48 chairs in row 20.

step-by-step explanation:

y = | -2(-2) |     →     y = | 4 |     →     y = 4       ⇒   (-2, 4)

y = | -2(-1) |     →     y = | 2 |     →       y =   2       ⇒   (-1, 2)    

y = | -2(0) |     →     y = | 0 |     →       y = 0         ⇒   (0, 0)

y = | -2(1) |   c →     y = | -2 |     →     y =   2         ⇒   (1, 2)    

y = | -2(2) |     →     y = | - 4 |     →     y =   4         ⇒   (2, 4)