Question

5. If nCn-4 = 15, find n

Answer 1

nCr-4)-15

nl/4!(n-4)=15

n(n-1)(n-2)(n-3)/24=15

n(n-1)(n-2)(n-3)=360

6.5.4.3.2 = 360

Then n = 6

Answer 2

Step-by-step explanation:

nCn-4=15. nC(n-4)=15. n!/4!(n-4)!=15. n(n-1)(n-2)(n-3)/24=15. n(n-1)(n-2)(n-3)=360. 6*5*4*3*2=360. then answer is 6