C420+2.C320+C220-C1822=
0
1242
7315
6345
Explanation for the correct option:
Solve the given series using standard formulas
C420+2.C320+C220āC1822
=C420+C320+C320+C220āC1822
=C421+C321āC1822 āµCrn+Cr+1n=Cr+1n+1
=C422āC1822=C1822āC1822=0 āµCrn=Cnārn
Hence, Option āAā is Correct.