Question

Find tn for following A.P. and also find 45th term A.P. is 6, 1/2 5,....​

Answer 1

Step-by-step explanation:

first term a=5, last term l=45 and S

n

= 400

Since, S

n

=

2

n

(a+l)

⇒400=

2

n

(5+45)

⇒400=

2

n

(50)

⇒400=n(25)

⇒n=16

Since, l=a+(n−1)d

⇒45=5+(16−1)d

⇒45−5=(15)d

⇒40=15d

⇒d=

15

40

⇒d=

3

8