Question

find the sum of first 20 terms of the AP 2.5.8​

Answer 1

Answer:

2+5+8 =15

in ap add numbers and decided by no of no so

15/3=5

Answer 2

if there are commas among 2.5.8then the answer may be--

d=5-2=3

Sn=n/2(2a+(n-1)d)

S20=20/2(2×2+(20-1)3)

S20=10(4+19×3)

S20=10(4+57)

S20=10×61

S20=610