Waste less time on Facebook — follow Brilliant.
×

Problem I could not solved.

(n-3)(n-4)!/(n-5)(n-6)!=?

Note by Mehdi Balti
2 years, 6 months ago

No vote yet
1 vote

  Easy Math Editor

MarkdownAppears as
*italics* or _italics_ italics
**bold** or __bold__ bold

- bulleted
- list

  • bulleted
  • list

1. numbered
2. list

  1. numbered
  2. list
Note: you must add a full line of space before and after lists for them to show up correctly
paragraph 1

paragraph 2

paragraph 1

paragraph 2

[example link](https://brilliant.org)example link
> This is a quote
This is a quote
    # I indented these lines
    # 4 spaces, and now they show
    # up as a code block.

    print "hello world"
# I indented these lines
# 4 spaces, and now they show
# up as a code block.

print "hello world"
MathAppears as
Remember to wrap math in \( ... \) or \[ ... \] to ensure proper formatting.
2 \times 3 \( 2 \times 3 \)
2^{34} \( 2^{34} \)
a_{i-1} \( a_{i-1} \)
\frac{2}{3} \( \frac{2}{3} \)
\sqrt{2} \( \sqrt{2} \)
\sum_{i=1}^3 \( \sum_{i=1}^3 \)
\sin \theta \( \sin \theta \)
\boxed{123} \( \boxed{123} \)

Comments

Sort by:

Top Newest

Comment deleted Jul 20, 2015

Log in to reply

Can you explain it :)

Mehdi Balti - 2 years, 6 months ago

Log in to reply

@Mehdi Balti, could you please clarify what the problem is? Thanks.

Victor Loh - 2 years, 6 months ago

Log in to reply

It's factorial and the answer will be in positive integer.Not in decimal (n-3)(n-4)!/(n-5)(n-6)!=?

Mehdi Balti - 2 years, 6 months ago

Log in to reply

Based on how you've clarified the problem, I'm assuming you wish to find the value of

\[x = \frac{(n-4)!(n-3)}{(n-6)!(n-5)},\]

where \(x\) is a positive integer.


Note that

\[\begin{align} x &= \frac{(n-4)!(n-3)}{(n-6)!(n-5)} \nonumber \\ &= \frac{(n-3)[(n-4)(n-5)(n-6)\cdots(3)(2)(1)]}{(n-5)[(n-6)(n-7)(n-8)\cdots(3)(2)(1)]} \nonumber \\ &= \frac{(n-3)(n-4)(n-5)!}{(n-5)!} \nonumber \\ &= (n-3)(n-4) \nonumber \end{align}\]

This value is different for different values of \(n\). I'm not sure if this is what you want, although \((n-3)(n-4)\) is clearly a positive integer for positive integer values of \(n\). Please clarify further. Thanks!

Victor Loh - 2 years, 6 months ago

Log in to reply

Yes n value is positive integer.Really thanks @Victor Loh I got it completely Now :) Thumps up for u Cheers :)

Mehdi Balti - 2 years, 6 months ago

Log in to reply

If I would not given the value but say that it's positive integer then how would you solve this ?Answer should be in positive integer.

Mehdi Balti - 2 years, 6 months ago

Log in to reply

×

Problem Loading...

Note Loading...

Set Loading...