Question

find the sum of each APs 2,7,12,17,....to 19 term

Answer 1

a=2
d=5
n=19
by using s=n/2{2a+(n-1)d}
we get
s=893

Answer 2

Put values in formulae
N/2(2a+(n-1)d)
19/2(2*2+(19-1)*5)
19/2(4+18*5)
19/2(4+90)
19/2*94
19*47
893 ans/.