Question

61+62+63+..............+110=?​

Answer 1

Answer:

In this question ,

The formula of A.P is used.

= an= a + ( n -1)d

an =119 , a = 61 ,d = 1

put the value in formula

110 = 61+(n-1) 1

110-61 = (n-1)1

39=(n-1)1

39/1=(n -1)

39+1 = n

40 =n

Answer 2

Answer:

Step-by-step explanation:

L=a+(n-1)d

L=last number

A=first number

D=common difference

Substitute formula:

100=61+(n-1)1

100-61=(n-1)

49=n-1

49+1=n

50=n

Sum of Ap=n/2(a+l)

=50/2(61+110)

=25×171

=4275