Galal R.

asked • 08/16/16

i got this weird permutation equation

30 p x = 30 p x+2y
i want the value of x and y please

Arturo O.

Is the equation uploaded correctly?
 
If 30px = 30px + 2y, then y = 0 and x can be anything.
Report

08/16/16

Galal R.

yeah it was uploaded correctly thnx
Report

08/16/16

Arturo O.

Galal,
 
I am confused about the notation.  Are you trying to solve
 
P(30,x) = P(30, x+2y)
 
with
 
P(30,x) = 30! / (30-x)!
 
and
 
P(30, x+2y) = 30! / [30-(x+2y)]!
 
for x and y?
 
Report

08/16/16

Galal R.

Yes Arturo 
Report

08/16/16

Arturo O.

Then 
 
30! / (30-x)! = 30! / [30-(x+2y)]! ⇒
 
(30-x)! = [30-(x+2y)]!
 
There is a trivial solution:
 
y = 0
0 ≤ x ≤ 30, x integer
 
I am at a loss to find a non trivial solution.
Report

08/16/16

1 Expert Answer

By:

Arturo O. answered • 08/20/16

Tutor
5.0 (66)

Experienced Physics Teacher for Physics Tutoring

See tutors like this
See tutors like this
If P(30,x) = P(30, x+2y) then

30! / (30-x)! = 30! / [30-(x+2y)]! ⇒ (30-x)! = [30-(x+2y)]!

There is a trivial solution:

y = 0
0 ≤ x ≤ 30, x integer

I am at a loss to find a non trivial solution.
 
In general, if
 
(30 - x)! = [30-(x+2y)]!
 
then 
 
30 - x = 30 - (x + 2y)
 
Then y = 0, and we are left with an identity:
 
30 - x = 30 - x
Upvote • 0 Downvote
More
Report

Still looking for help? Get the right answer, fast.

Ask a question for free

Get a free answer to a quick problem.
Most questions answered within 4 hours.

OR

Find an Online Tutor Now

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.