Question

find the sum of first 20 terms of A• p• 3,7,11,15 using the formula
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Answer 1

Step-by-step explanation:

This is your answer.

All the best for rest of the sums.

Answer 2

Step-by-step explanation:

d=7-3=4

S=n/2(a+l)

l=a+(n-1)d=3+ (20-1)(4)=3+(19*4)=3+76=79

S=20/2(3+79)=10*82=820