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

Answer:

n=40 and sn=7420

Step-by-step explanation:

a1=10

l=361

d=9

an=a+(n-1)d

361=10+(n-1)9

=10+9n-9

=1+9n

9n=361-1=360

n=360/9

=40

therefore, 40 no. of terms

total sum= sn= s40

s40=40/2 (2*10 + 39*9)

=7420

thank you.

Answer 2

Answer:

Answer is in the photo.

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