Question

find the common difference of an ap was first isfind the common difference of an ap was first is 100 and the sum of first 6 terms is 5 time the sum of the next six terms
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Answer 1

here first term is a= 100 and sum of 6 term that means first to six term s6= 5 times the next six term that mean s6= 5(s14-s6 )

put the formula according this

an= a+ (n-1) d

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