What is the Correct Value of r if 9!/(9-r)! = 840?

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  • Thread starter mathdad
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In summary, the equation "Find r - 9!/(9 - r)! = 840" is asking for the value of r that satisfies the equation and the exclamation mark (!) is the factorial symbol, which means to multiply a number by all the positive integers less than it. The value of 9! is 362880. To solve this equation, you can use algebraic methods such as simplifying the equation, isolating the variable r, and solving for r using basic arithmetic operations. There is only one possible value for r that satisfies the equation because the equation is a mathematical statement that is either true or false, and there can only be one solution that makes it true.
  • #1
mathdad
1,283
1
9!/(9 - r)! = 840

I found r to be 4.

Is this correct?
 
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  • #2
RTCNTC said:
9!/(9 - r)! = 840

I found r to be 4.

Is this correct?

$\dfrac{9!}{(9-4)!} = \dfrac{9!}{5!} = 9 \cdot 8 \cdot 7 \cdot 6 = 3024$

there is no solution to the equation $\dfrac{9!}{(9-r)!} = 840$ for $0 \le r \le 9 \, , \, r \in \mathbb{Z}$
 
  • #3
I messed up in my calculation. Thanks.
 

FAQ: What is the Correct Value of r if 9!/(9-r)! = 840?

What is the equation "Find r - 9!/(9 - r)! = 840" asking for?

The equation is asking for the value of r that satisfies the equation and makes it true.

What does the exclamation mark (!) mean in the equation?

The exclamation mark is the factorial symbol, which means to multiply a number by all the positive integers less than it.

What is the value of 9!?

The value of 9! is 362880 (9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1).

How do I solve this equation?

To solve this equation, you can use algebraic methods such as simplifying the equation, isolating the variable r, and solving for r using basic arithmetic operations.

Is there only one possible value for r that satisfies the equation?

Yes, there is only one possible value for r that satisfies the equation. This is because the equation is a mathematical statement that is either true or false, and there can only be one solution that makes it true.

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