Question

What is the explicit formula for the sequence 3, 7,

11, 15, 19, ...?
an = 2n +1
an = 2n-1
an = 4n +1
O an=40-1
DONE

Answer 1

an = 4n - 1

a1 = 3

a2 = 7 = 3 + 4

a3 = 11 = 3 + 4.2

a4 = 15 = 3 + 4.3

a5 = 19 = 3 + 4.5

.....

=> this is a arithmetic with a1 = 3 and d = 4

=> an = 3 + 4(n - 1) = 4n - 1