Question

15 th term of series 3,7,13,21 is ​

Answer 1

Answer: n=4

Step-by-step explanation:

a=3, an=15, d=7-3=4, n=?

An=a+(n-1)d

15=3+(n-1)4

15-3=4n-4

4n=12+4

n=16/4

n=4

Answer 2

Answer:

a=3

d=7-3=4

an=15

n=?

Step-by-step explanation:

an=a+(n-1) d

15=3+(n-1) 4

15-3=(n-1) 4

12=(n-1) 4

12÷4=(n-1)

3=(n-1)

n=4