How to Correctly Solve L = 1800cc - 72cm?

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Discussion Overview

The discussion revolves around solving a problem related to finding the length of a rectangular box that must hold a specific volume, given its width and height. Participants explore the mathematical relationships involved in the problem, including the correct interpretation of units and operations.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant expresses confusion about the equation L = 1800cc - 72cm, questioning how to proceed with finding the length.
  • Another participant points out that subtracting a length from a volume does not make sense and requests the complete problem for clarification.
  • A participant provides the full problem, which involves calculating the length of a box given its volume, width, and height.
  • Participants discuss the formula for volume (V = l * w * h) and how to isolate the length (l) by rearranging the equation.
  • There is an explanation of the principle that performing the same operation on both sides of an equation maintains its validity.
  • One participant acknowledges understanding the rearrangement of the equation to solve for length.
  • A later reply humorously suggests that a misreading of symbols may have led to the initial confusion regarding the equation.

Areas of Agreement / Disagreement

Participants generally agree on the need to clarify the problem and the mathematical principles involved, but there is no consensus on the initial equation presented, as it was deemed incorrect by some. The discussion remains unresolved regarding the initial misunderstanding of the equation.

Contextual Notes

There are limitations in the initial problem statement, particularly regarding the mixing of units (volume and length) and the need for clarity in the mathematical operations involved.

Superman89
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I'm stuck can anybody help me? (Note: I'm looking for the length.)

1,800cc-72cm=L

What do I do next?
 
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Well, what you've posted does not make sense. You cannot subtract a length (cm) from a volume (cc). Perhaps you can show us the WHOLE problem?

- Warren
 
Well maybe I haven't got it written out right. Can I give you the problem and you work it out and show me how to do it?
 
Like I just said, yes, please post the entire problem.

- Warren
 
Here it is.

How long must a rectangular box be in oder to hold 1,800 cubic centimeters if its width is 12 centimeters and its height is 6 centimeters?
 
Originally posted by Superman89
Here it is.

How long must a rectangular box be in oder to hold 1,800 cubic centimeters if its width is 12 centimeters and its height is 6 centimeters?
Okay, you've already posted this once. Why did you start a new thread on it?

Here's how to solve it:

[tex]\begin{equation*}<br /> \begin{split}<br /> V &= w \cdot l \cdot h\\\\<br /> l &= \frac{V}{w \cdot h}\\\\<br /> l &= \frac{1,800}{12 \cdot 6}<br /> \end{split}<br /> \end{equation*}[/tex]

Does this make sense?

- Warren
 
Let me see if I've got this straight.

When "w" and "h" are brought arcross the "=" sign, the oppisite must be done.

[itex]V=l*w*h[/itex]

[itex]\frac {V}{w*h}=l[/itex]

Right?
 
It's easier to think about it this way: performing the same operation to both sides of an equation does not change the equation's validity.

In other words, if you have an equation like [itex]a=b[/itex], adding one to both sides of it does not change its truth: [itex]a+1=b+1[/itex] is also true.

In the case of the equation [itex]V = l \cdot w \cdot h[/itex], you can divide both sides by [itex]w \cdot h[/itex] and not change the equation's valitiy.

[tex]\begin{equation*}<br /> \begin{split}<br /> \frac{V}{w \cdot h} &= \frac{l \cdot w \cdot h}{w \cdot h}\\\\<br /> \frac{V}{w \cdot h} &= l<br /> \end{split}<br /> \end{equation*}[/tex]

- Warren
 
I see what you mean. So my answer is going to be [tex]l &= \frac{1,800}{12 \cdot 6}\end{split}\end{equation*}[/tex]?
 
  • #10
Didn't I already say that?

- Warren
 
  • #11
Thanks! You've been a real good help Dude!
 
  • #12
Originally posted by Superman89
Thanks! You've been a real good help Dude!
Anytime. :smile:

- Warren
 
  • #13
Originally posted by Superman89
I'm stuck can anybody help me? (Note: I'm looking for the length.)

1,800cc-72cm=L

What do I do next?

Well fisrt thing I'd do is to get that X-Ray vision tested there Superman. ;)

Looks to me like when you copied the "answer" of L = 1800cc - 72 cm from whoever that you misread a divide symbol for a minus symbol.
 

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