Question

25 POINTS

A fireplace contains 46 bricks along the bottom row. If each row increases by 4 bricks, what is the function that shows the bricks on the 12th row?

Answer 1

a + (n - 1)d

a is 46, the initial.

n is the nth term, or in this case 12

d is difference, which is 4

plug this info in....

46+ (12-1)4

=90

Answer 2

Each row increases by 4, so the second row would be 46 +4 which equals 50. Then the 3rd row would be 50 +4.

So the 1st number is a(1) = 46 ( row 1 has 46 bricks)

The common difference is adding 4 bricks, so d = +4

The function becomes a(n) = a(1) +(n-1) * d

where n is the number of the row you want to find the total of.

Now you want to know the 12th row so replace n with 12:

a(12) = 46 + (12-1)*4

a(12) = 46 + ( 11*4 )

a(12) = 46 + 44

a(12) = 90 bricks