Question

the first term of an A.P is 5 and the common difference is 10.complete the following activity to find the sum of first 10 terms of the A.P​

Answer 1

Sum of n terms equal to n/2[2a+(n-1)d]
Here a = 5 , d = 10 and n=10
=10/2[2(5)+(10-1)10]
=5[10+90]
=5[100]
=500

Answer 2

Answer:

a1=5

d=10

n=10

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

= 10/2(2×5+(10-1)10)

=5×[10+90]

500