Factorials: 7x!/5!= 7!/120, (2(3)!)!, 2(3)!

[nycfunnygirl]

Hi there! I am have problems with Factorials. Your help is greatly appreciated! the problem is

7x!/5!= 7!/120

I am not understanding at the point of cross multiplying. Do I break down the factorial first? Can someone show me how I would do this problem.

Also, if the problem is (2(3)!)!

how do I do this? Is it just 6x5x4x3x2x1 ? Is that the answer OR do I break down each of those into factorials?

Another problem is 2(3)!

do I multiply the 2x3 first and then answer is 6! ? HELP HELP HELP!

THanks in advance!

 

[stapel]

I am have problems with Factorials.

To learn what factorials are and how they work, try here. :wink:

7x!/5!= 7!/120

I will guess that this is an equation and that you're supposed to solve for the value of x:

. . . . .\(\displaystyle \frac{(7)(x!)}{5!}\, =\, \frac{7!}{120}\)

Since 5! = 120, the above obviously means the same as:

. . . . .\(\displaystyle (7)(x!)\, =\, 7!\)

Since 7! means 1 * 2 * 3 * 4 * 5 * 6 * 7, then:

. . . . .\(\displaystyle (7)(x!)\, =\, 1\times 2\times 3\times 4\times 5\times 6\times 7\)

Divide through by 7, and relate the value of "x" to what you end up with on the right-hand side.

(2(3)!)!

I will guess that you are supposed to evaluate this expression. If so, find the value of 3!. Then multiply this by 2. Then find the factorial of the resulting value.

2(3)!

Find the value of 3!. Multiply by 2.

 

[nycfunnygirl]

THANK YOU!!!! You should be a math professor! You are much better than mine. He sucks.