Question

find the sum of terms 40 to 60​

Answer 1

40,41,42,43,......60

a=40

d=1

therefore ...60=40+(n-1)1

60-40+1=n

n=21

now ......s(21)=(21/2)(40+60)

=50×21=1050

Answer 2

Step-by-step explanation:

40,41,42,...................,60

a = 40 , d = 1 , n = 21

Sn = 21/2 {2(40) + (21-1)1}

= 21/2 {80 + 20}

= 21/2 * 100

= 21 * 50

= 1050