Question

Find the value of
i) $\rm ^{14}C_{5}$
ii) $\rm ^{90}C_{2}$

Answer 1

Answer:

i) 2002

ii) 4005

Step-by-step explanation:

We know the formula of combination as shown below

nCr =  n! / r! (n - r)!

Therefore,

i)  14C5 = n = 14; r = 5.

so, 14! / 5!(14-5)! = 14! / 5! * 9! = (14*13*12*11*10)/5! = 2002. [Ans]

ii)90C2 =  n = 90; r = 2.

so, 90!/2! * (90-2)! = (90 * 89) / 2! = 4005. [Ans]

We have to try to simplify it by canceling the large terms.