Question

in an AP if S25 = 1275 and S24 = 1176 then a25 =​ a)99 b)98 c)97 d)96​

Answer 1

Answer:

a)99

Step-by-step explanation:

first- S²⁵=25a+300d

S²⁴= 24a+276d

now,. 25a +300d=1275-------(1). ×24

24a + 276d = 1176-------(2)×25

by using elimination method

We have, 600a+7200d=30600

-(600a+6900d=29400)

=300d=1200

d=4

by putting value of d in (1)

we have a= 3

thus, a 25 = a+ 24 d

= 3 +24× 4

=3+96

= 99