Question

29. Find the sum of first 25 terms of the AP 30,
a
26, 22, ...
​

Answer 1

Answer:

the sum of first 25 terms is 1950

Step-by-step explanation:

here, a=30, d=-4, n= 25.

we know that,

Sn=n/2[2a-(n-1)d]

S25=25/2[2(30)-(25-1)(-4)]

S25=25/2[60+96]

S25=25/2[156]

S25=25×78

S25=1950