Question

the second and fourth term of AP are 12 and 20 respectively then find the sum of first 25 terms​

Answer 1

the second and fourth term of AP are 12 and 20 respectively then find the sum of first 25 terms

i hope that the answer is 24000

Answer 2

Answer

t2=12

t4=20

So as per the condition

t1=8

t3=16

Therefore, a=8 and d=4

Sn=n/2×(2a+(n-1)d)

S25= 25/2×(2×8+(25-1)4)

= 25/2×(16+96)

= 25/2×112

= 25×56

= 1400

Therefore, S25=1400

Hope it will help you