Question

find the sum of 20 terms in AP 5+10+15 using suitable formula​

Answer 1

Answer:

here u can see a=5 common difference

d=10-5

d=5

now,

sum of terms = n/2(a+(n-1)d)

so,

sum=20/2(5+(20-1)5)

sum=10*100

sum=1000

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