Find The Number Of Terms In The Arithmetic Sequence In Which A1= 2.5 D= 1.5 And An= 13

Find the number of terms in the arithmetic sequence in which a1= 2.5 d= 1.5 and An= 13

 

Answer:

There are 8 terms in the given series or 13 is the 8th term.

Step-by-step explanation:

Arithmetic sequence general rule:

an = a₁ + (n-1)(d)

Where:

an = last term in a sequence ⇒ 13

a₁ = first term ⇒ 2.5

d = common difference  ⇒  1.5

n = number of terms  ⇒ Uknown

Substitute to find n:

13 = 2.5 + (n-1)(1.5)

13 = 2.5 - 1.5 + 1.5n

13 = 1 + 1.5n

1.5n = 13-1

1.5n/1.5 = 12/1.5

n = 8

There are 8 terms in the given series or 13 is the 8th term.