Question

find the sum of 25 terms of AP. whose middle term is 30​

Answer 1

Step-by-step explanation:

A(13) = 30

a + 12d = 30 -------(1)

S(25) = 25/2 {2a + (25-1)d}

= 25/2 {2a + 24d}

= 25/2 {2(a+12d)}

= 25/2 {2 * 30} (equation (1) से )

= (25/2)*60

= 25*30=750

= 25/2