Question

The first term of an A.P is 5 and its last term is 45. If sum all terms
is 125 then how many terms are there in that A.P ?

Answer 1

Answer:

Values of n = 16 and

Values of n = 16 and d = 8/3

Step-by-step explanation:

Let a , d , l are first term , common difference and last term of an A.P , respectively.

given ,

a = 5, l = 45

We know that,

Substitute values of a and l , we get,

=> 45 = 5+(n-1)d

=> 45-5 = (n-1)d

=> (n-1)d=40 ----(1)

\* given *\

Now ,

Substitute n=16 in equation (1), we get

(16-1)d = 40

=> 15d =40

=> d = 40/15

=> d = 8/3

Therefore,

Values of n = 16 and

d = 8/3

Step-by-step explanation:

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