Download the app

Questions  

The minimum number of terms from the beginning of  the series 20+2223+2513+so that the sum may 
exceed 1568, is

Remember concepts with our Masterclasses.

80k Users
60 mins Expert Faculty Ask Questions
a
25
b
27
c
28
d
29

Ready to Test Your Skills?

Check Your Performance Today with our Free Mock Tests used by Toppers!

detailed solution

Correct option is D

It is in A.P. for which a=20,d=223=83Now, Sn>1568⇒    n240+(n−1)83>1568⇒    n2×112+8n3>1568⇒    n2+14n>68×1568=1176⇒    n2+14n−1176>0 or     (n+42)(n−28)>0As n is positive, n – 28 > 0 i.e., n > 28 ∴Minimum value of n = 29.


Similar Questions

If the sum of first n terms of an AP is cn2, then the sum of squares of these  n terms is 


whats app icon
phone icon