Question

if np4:n-1p5=3:1 find value n​

Answer 1

Given,

n−1

P

5

n

P

4

=3

or,

(n−1)(n−2)(n−3)(n−4)(n−5)

n(n−1)(n−2)(n−3)

=3

or, n=3(n−4)(n−5)

or, 3n

2

−27n+60=n

or, 3n

2

−28n+60=0

or, 3n

2

−18n−10n+60=0

or, 3n(n−6)−10(n−6)=0

or, (3n−10)(n−6)=0.

Since n is a natural number then n=6.