Question

the first term of an arithmetic sequence is 8, the last term id 56 and the sum is 416. find the number of terms

Answer 1

13

Explanation:

first term (a) = 8

last term ( ) = 56

sum (S) = 416

number of terms (n) = ?

equation

S = n/2 (a+)

416 = n/2 (8+56)

416 = n/2 (64)

416 = 32n

n = 416/32 = 13