boxes volume

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
wkaidy
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boxes volume

Postby wkaidy » Sat Nov 17, 2012 11:47 pm

havin trouble with this problem... the volume of the larger rectangular box is three times the volume of the smaller rectangular box what is the value of x?

the sides of the large box are as follows l= x=2, w= x=1 h=x all three sides of the small box are x how would i go about solving this? thank you

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stapel_eliz
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Postby stapel_eliz » Sat Nov 17, 2012 11:56 pm

wkaidy wrote:havin trouble with this problem... the volume of the larger rectangular box is three times the volume of the smaller rectangular box what is the value of x?

the sides of the large box are as follows l= x=2, w= x=1 h=x all three sides of the small box are x how would i go about solving this? thank you

The exercise asks for the value of x, but then you say that the exercise has given you two values for x: x = 2 and x = 1. Also, h = l = w = h. This does not make sense.

Kindly please reply with the exact text of the exercise or, if the above is the exact text, please ask your instructor for a corrected version. Thank you! :wink:

wkaidy
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Re: boxes volume

Postby wkaidy » Sun Nov 18, 2012 12:01 am

sorry l=x+1 w=x h=X+2

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maggiemagnet
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Re: boxes volume

Postby maggiemagnet » Sun Nov 18, 2012 12:25 am

wkaidy wrote:sorry l=x+1 w=x h=X+2

I'll guess that "X" is meant to be the same as "x". (This is usually not true in math, so please say if I'm wrong!)

What is the formula for the volume V of a rectangular solid (or box, in this case) with width w, length L, and height h? Plug the expressions they gave you into the formula for the variables. Simplify to get the volume of the larger box. Do the same thing for the smaller box, with w = L = h = x. Then create an equation that says "(large volume) is (three times of)(small volume)". Solve the equation for x.

If you get stuck, please write back showing your work for the steps I gave you. Thanks!
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wkaidy
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Re: boxes volume

Postby wkaidy » Sun Nov 18, 2012 12:31 am

so i get
3x=(x)(x+2)(x+1)
so 3x= x^2+2x^2+2x and im stuck

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maggiemagnet
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Re: boxes volume

Postby maggiemagnet » Sun Nov 18, 2012 12:33 am

wkaidy wrote:so i get
3x=(x)(x+2)(x+1)
so 3x= x^2+2x^2+2x and im stuck

Where is the 3x coming from? What does the sum in your second equation relate to? (It's not volume.) What is your simplified expression for the larger volume? What is your simplified expression for the smaller volume? What is your equation that relates the two volume expressions? Thanks!
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wkaidy
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Re: boxes volume

Postby wkaidy » Sun Nov 18, 2012 12:37 am

I dont fully understand would you mind giving me a run down on how to do this type of problem i have to do a bunch of them and am compleatly lost

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maggiemagnet
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Re: boxes volume

Postby maggiemagnet » Sun Nov 18, 2012 1:04 am

wkaidy wrote:I dont fully understand would you mind giving me a run down on how to do this type of problem i have to do a bunch of them and am compleatly lost

I did give you a run-down: They gave you expressions for L, w, and h of the big box in terms of x. Plug these into the formula for the volume V of a box with length L, width w, and height h. This gives you an expression for the big volume in terms of x. What expression do you get? They also gave you expressions (all the same one-variable expression) for L, w, and h of the small box in terms of x. What expression do you get? They also gave you a relationship: "(the big volume) is (three times of)(the small volume)". Plug your expressions into the equation, and solve.
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