What formula should you use to solve this problem
arithmetic sequence, arithmetic series, geometric sequence, or geometric series.? ( Dont solve problem)

Question

What formula should you use to solve this problem
arithmetic sequence, arithmetic series, geometric sequence, or geometric series.? ( Dont solve problem)

coconut · Answer

A fireplace contains 46 bricks along its bottom row. If each row above decreases by 4 bricks, how many bricks are on the 12th row?

coconut · Answer

dont solve! :) also can you explain why you use that formula

anonymous · Answer

I guess it's arithmetic, because it decreases by 4 bricks which means x,x-4 ,(x-4)-4 , ...
(I think)
the formula is
$$\LARGE a_n=a_1+(n-1)d$$
since d=-4
you have to find a_12
and you have a_1=46

... IMAO :)

anonymous · Answer

do you get it ? :) @coconut

coconut · Answer

yes thank you so much:)

anonymous · Answer

You're welcome xD