Question

the sum of first 20terms of arthemetic series 5+10+15+using suitable formula​

Answer 1

Answer:

1050

Step-by-step explanation:

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

a=5; d=5; n=20

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

 = 10(10+[19]5)

 =10(10+ 95)

 =10(105)

 = 1050