How many terms are in the following sequence that follows? 3,7,11,....,439

2 answers

looks like an arithmetic sequence with
a = 3
d = 4
term(n) = 439
a + (n-1)d = 439
3 + (n-1)(4) = 439
4n - 4 = 436
4n = 440
n = 110

there are 110 terms
arithmetic sequence
Xn - a + d(n-1)
here a = first term = 3
d = constant difference = 4
Xn = 439
so
439 = 3 + 4(n-1)
439 = 3 * 4 n - 4
440 = 4 n
n = 110