Question

find the sum of 25 terms of an A.P whose middle term is 20​

Answer 1

Answer:

Here,

n=25

(a1 + a25)/2 = 20

=(a1 + a25)= 40

 

sum of ap =n(a1+a25)/2

                =25*40/2

                =1000/2

                 = 500.

Answer 2

Given
Number of terms in the A.P (n) = 25

Middle term = 20

To find:

The sum of the terms.

Solution:

Since the middle term is 20, we can say that:

(a₁ + a₂₅)/2 = 20

= (a₁ + a₂₅)= 40

Now, the sum of the terms of the A.P will be:

=n(a₁ + a₂₅)/2

=25 × 40/2

=1000/2

= 500

Thus, the sum of the 25 terms of the A.P will be 500.