The first and the last terms of an AP are 10 and 361 respectively. If its common difference is 9 then find the number of terms and their total sum?
Answers
Answered by
1
Answer:
361 is equal to 10+(n-1)9
351 is equal to 9n-9
360 is equal to 9n
number of terms is equal to 40
Answered by
1
Answer:
given,a=10
an=361
d=9
an=a+(n-1)d
n-1=(an-a)/d
=(361-10)/9
=39
n=40
sn=n/2(an+a)
=40/2(361+10)
sn=7420
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