Question

6+13+20+........+97

Find the sum of the following

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Answer 1

here, a=6 and d=7

97=a+(n-1)d

97=6+(n-1)7

n-1=13

n=14

so, sum= (n/2)×(2a+(n-1)d)

= 7×103

= 721

Answer 2

Answer:

a=6 and d=7

97=a+(n-1)d

97=6+(n-1)7

n-1=13

n=14

sum={(n/2)×(2a+(n-1)d}

=7×103

=721

thanks