If C(20, n+2)=C(20, n-2) , then what is n equal to?

Step-by-step solution

20 (n+2) = 20 (n-2) 20! (n+2)!(20-n-2)! = 20! (n-2)!(20-n+2)! aligned & (22-n)! (18-n)! = (n+2)! (n-2)! & (22-n)(21-n)(20-n)(19-n) & =(n+2)(n+1) n (n-1) aligned For n=10 aligned & (22-10)(21-10)(20-10)(19-10) & =(10+2)(10+1) 10 (10-1) & 12 11 10 9=12 11 10 9 aligned Hence, n=10 .