If C1518+2(C1618)+C1617+1=C3n, then n=?
19
20
18
24
Finding the value of n:
Given,
c1518+c1618+c1618+c1617+1=c3n
As we know,
cr+1n+crn=cr+1n+1
⇒c1619+c1618+c1617+c1717=c3n
⇒ c1619+c1618+c1718=c3n
⇒ c1619+c1719=c3n
⇒ c1720=c3n
⇒ c320=c3n
∴n=20
Hence, option(B) is correct.
Determine n if
(i) (ii)