Question

Find the sum of 20 terms of the AP √2, 2√2,3√2,...

Answer 1

Answer:

a= 2½

n= 20

d= a3-a2 = 2½

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

sn= 20/2(2*2½+19*2½)

sn= 10*21*2½