Question

Find r ,if 5 4Pr = 6 5P3-1
From permutation and combination chapter​

Answer 1

Find r ,if 5 4Pr = 6 5P3-1:

Good question,

Here is your perfect answer!

5 * 4Pr = 6* 5P2

=) 5 * 4! /(4-r)! = 6* 5!/(5-2)!

=) 5 * 4!/(4-r)! = 6*5!/3!

=) 5 * 4*3*2*1 /(4-r)! = 6*5*4

=) 1 = (4-r)!

=) r = 4-1 = 3.

Answer 2

Heya...

Thanx for the question...