Question

find the common difference of a A.P. whose first term is 100 and the sum of whose first six term is five times the sum of the next six terms​

Answer 1

Answer:

hope it helps you.....

Answer 2

Answer:

1. a=100

• s6=n/2{2a+(n_1)d}
• =6/2{2 ×100 +(6-1)d}
• =3{200+5d}

s12=6{200+11d}

=1200+66d-600-15d

according to question,

600+15d=5(600+51d)

255d-15d=600-3000

240d=-2400