22 + 42 + 62 .. ... ... .. +322 = কত?
সমাধান
সঠিক উত্তর: Option A
22 + 42 + 62 .. ... ... .. +322 = কত?
= (2.1)2 + (2.2)2 + (2.3)2 + ----- (2.16)2
=22 ( 12 + 22 + 33 + -------+162)
= 4 × {n(n + 1)(2n+1)}/6
= 4 × (16 × 17 + 33)/2
= 5984