Question

solve for n P(n,3) = 60

Answer 1

I'm assuming the P means Permutations.. do you know the formula?

Answer 2

yes

Answer 3

P(n,r) = n!/(n-r)!

Answer 4

So I'm assuming they want us to work backwards..

\(\large P(n, r ) = 60 = \frac{n!}{(n-3)!}\)

And we know that that \(n> 3 \)

Answer 5

yeah, for sure :)

Answer 6

I don't think they'd make the problem too difficult.. so I'd suggest just plugging in values for n that are greater than 3.

So if we try 4; 4! would equal 24, which is too small and not equal to 60. So 4 won't work.

Now trying 5: \(\large P(5, 3) = \frac{5!}{(5-3)!} = \frac{120}{2!}\)

And what's 120/2?

Answer 7

how to solve this then? i'm required to show a solution

Answer 8

\[0=n ^{3}-3n ^{2}+2n-60\]

Answer 9

i have went all until this equation, and i'm stuck

Answer 10

but 5's gonna work for that equation for sure

Answer 11

I'm not sure if they want you to go into it that deep, I think just plugging in values would suffice

Answer 12

yeah they do! and it's HORRIBLE

Answer 13

but thanks anyway :)