Question

a=-18.9 d=2.5 n=? an=3.6

Answer 1

Given :

• First term ( a ) = - 18.9
• Common difference ( d ) = 2.5
• Last term ( Aₙ ) = 3.6

____________________________

To Find :

• Number of terms ( n )

____________________________

Solution :

By using A.P formula

★ Aₙ = a + ( n - 1 ) d

→ 3.6 = - 18.9 + ( n - 1 ) 2.5

→ 3.6 + 18.9 = ( n - 1 ) 2.5

→ 22.5 = ( n - 1 ) 2.5

→ n - 1 = 22.5/2.5

→ n -1 = 9

→ n = 9 + 1

→ n = 10

∴ Number of terms in given A.P is 10

Answer 2

Step-by-step explanation:

Given :

First term ( a ) = - 18.9

Common difference ( d ) = 2.5

Last term ( Aₙ ) = 3.6

____________________________

To Find :

Number of terms ( n )

____________________________

Solution :

By using A.P formula

★ Aₙ = a + ( n - 1 ) d

→ 3.6 = - 18.9 + ( n - 1 ) 2.5

→ 3.6 + 18.9 = ( n - 1 ) 2.5

→ 22.5 = ( n - 1 ) 2.5

→ n - 1 = 22.5/2.5

→ n -1 = 9

→ n = 9 + 1

→ n = 10

∴ Number of terms in given A.P is 10