edited by
929 views

2 Answers

Best answer
2 votes
2 votes
Sum of given  n  terms in AP  is =   $n/2(2a+(n-1)d)$ , where n = no of term , a = intial term value , d = common difference

according to given question   sum of 11 terms in AP =  sum of 19 terms in AP

                                         $11/2(2a+10d) = 19/2(2a+18d)$

                                         $22a+110d=38a+342d$

                                        $16a+232d =0$ ------ (1)

similar  sum of 30 term in AP = $30/2(2a+29d)$

    multiply by 8 this , we get  =   $30/2(16a+232d)$

    from equation 1 ,  sum of 30 term in AP = $30/2(0)$ = $0$

So ans is option 1) =0
selected by
0 votes
0 votes
ans is 0.

Related questions

1 votes
1 votes
1 answer
5
go_editor asked Jan 14, 2016
2,913 views
A circle with radius $2$ is placed against a right angle. Another small circle is also placed as shown in the adjoining figure. What is the radius of the smaller circle?$...