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03212010  #1 
Join Date: Mar 2010
Posts: 9

Advanced functions problem
A box will be made of 2 identical pieces each with 3 sides. They will fit together to make a 6 sided box. Each piece will be cut from one piece of metal that is 20 cm by 20 cm by cutting out a square corner and folding up the two resulting flaps. What dimensions of the square cutout will produce a box with a volume of 1125 cm^3?
I tried solving it, and i came up with: 1125=(202x)(202x)(x) 1125=(40040x40x+4x^2)(x) 1125=(40080x+4x^2)(x) 1125=(4x^280x+400)(x) At this point i was clueless.. anybody? i mean if you factored it youd get 4(x10)^2(x) then im just clueless as to how this relates to the answer...please help me here math people. 
03232010  #2 
Join Date: Feb 2010
Posts: 388

Me, I'm really not good at this stuff so maybe you should email Mr.hui He might know.
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03232010  #3  
Join Date: Feb 2010
Posts: 117

problem
Quote:
So what i do have is a site called http://www.artofproblemsolving.org This place it is completely about math and people their are very good Either Middle School Classroom Math (1013) OR High School Basics (1216) 

03242010  #4  
Join Date: Dec 2008
Posts: 249

What about this?
Quote:
1125 = (20  x)(20  x)(x) 1125 = 400x  40x^2 + x^3 0 = x^3  40x^2 + 400x  1125 Solving the cubic equation gives x = 26.518, 5, and 8.486122 You can throw out the 26.518 number because 20  26.518 = 6.518 which is not possible. However, the other two values are the dimension of the square cutout, either 5 x 5, or 8.486122 x 8.486122 cm. 

03252010  #5 
Join Date: Feb 2010
Posts: 388

What he said ^^
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03252010  #6 
Join Date: Mar 2010
Posts: 9

Wow thanks alot...now i get it.

04012010  #7 
Join Date: Feb 2010
Posts: 388

Yeah Mas1 is very smart!
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