Question

P(n,6)=3p(n,5) what is the value of n.​

Answer 1

n = 10

Explanation:

3n1!/(n-4)! = (n-1)!/( n-1-5)

3n(n-1)(n-2)(n-3)(n-4) / N-4 -------- case1 ( cancel ( n-4) from top and bottom)

= (n-1)(n-2)(n-3)(n-4)(n-5)(n-6) / n-6 --------- case 2 ( Cancel n-6 from top and

bottom and also cancel n-1,

n-2, n-3 with case 1)

3n = ( n-4)(n-5)

3n = n² - 5n - 4n + 20

3n = n² - 9n + 20

0 = n² - 9n - 3n + 20

0 = n² - 12n + 20

0 = (n-2)(n-10)

n = 2 ( not valid) n = 10

Therefore n = 10