Question

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 ​

Answer 1

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• see the attachment above

Answer 2

Answer:

ok

Step-by-step explanation:

a=10 an=361 d=9

n=? sn=?

an=a+(n-1)d

361=10+(n-1)9

351/9=9n

n=40

sn=s40

s40=n/2(a+an)

=40/2(10+361)

=20(371)

s40=7420