Chiefinonhaze Posted April 27, 2011 Share Posted April 27, 2011 I started that 48/2(9+3) thread, and nobody knew the real answer. Obviously, the form of the problem was ambiguous. This one I simply cant figure out. It's part of my HW, and the answer I got was 340xy+240xz+240yz I only get three attempts on this online HW, and I've already used 2 ***************************************************************************************************** A storage building is planned which will have a rectangular base and a flat roof. The foundation (including floor) will cost $12 per square foot. The sides will cost $10 per square foot. The roof will cost $14 per square foot. a) Write an equation to express the construction cost of this building as a function of length x, width y, and height z. C(x,y,z)= ??????? Link to comment Share on other sites More sharing options...
SonOfWashington Posted April 27, 2011 Share Posted April 27, 2011 Woops. I messed this up initially. I assumed that each side had the same volume. Link to comment Share on other sites More sharing options...
Chiefinonhaze Posted April 27, 2011 Author Share Posted April 27, 2011 But in the foundation your including z, which is supposed to be the height....?? How would the height be included in the foundation. I feel like the foundation should be (12x)*(12y). Link to comment Share on other sites More sharing options...
Weganator Posted April 27, 2011 Share Posted April 27, 2011 CoF - Cost of floor: 12 * x * y CoWx - Cost of walls (x): 2 * 10 * x * z (2 walls, each 10xz) CoWy - Cost of walls (y): 2 * 10 * y * z (2 walls, each 10yz) CoC - Cost of ceilign: 14 * x * y (ceiling is parallel to floor) Cost = CoF + CoWx + CoWy + CoC C(x,y,z) = 12xy + 14xy + 20xz + 20yz = 26xy + 20xz + 20yz I was CS and Math back in school, so I hope I got it... Important note (EDIT): Price is in feet squared... so your units need to be feet squared... so you cant multiply square feet dollars by cubic feet units.. so each one needs to be a pair of variables!! Link to comment Share on other sites More sharing options...
SonOfWashington Posted April 27, 2011 Share Posted April 27, 2011 But in the foundation your including z, which is supposed to be the height....??How would the height be included in the foundation. I feel like the foundation should be (12x)*(12y). I guess I'm considering the foundation could be in the ground. Link to comment Share on other sites More sharing options...
Chiefinonhaze Posted April 27, 2011 Author Share Posted April 27, 2011 CoF - Cost of floor: 12 * x * yCoWx - Cost of walls (x): 2 * 10 * x * z (2 walls, each 10xz) CoWy - Cost of walls (y): 2 * 10 * y * z (2 walls, each 10yz) CoC - Cost of ceilign: 14 * x * y (ceiling is parallel to floor) Cost = CoF + CoWx + CoWy + CoC C(x,y,z) = 12xy + 14xy + 20xz + 20yz = 26xy + 20xz + 20yz I was CS and Math back in school, so I hope I got it... Why wouldn't the cost of the floor be 12x*12y? Link to comment Share on other sites More sharing options...
Slacky McSlackAss Posted April 27, 2011 Share Posted April 27, 2011 C(x,y,z) = 12xy+20xz+20yz+14xy Link to comment Share on other sites More sharing options...
Chiefinonhaze Posted April 27, 2011 Author Share Posted April 27, 2011 I guess I'm considering the foundation could be in the ground. I dont know man, you could be right. Every answer i've typed into this Homework is wrong. I only have one more try. Guess I would see if extremeskins could figure it out. Link to comment Share on other sites More sharing options...
Slacky McSlackAss Posted April 27, 2011 Share Posted April 27, 2011 Why wouldn't the cost of the floor be 12x*12y? because then you have $12/ft^2 * x ft. That wouldn't work. Link to comment Share on other sites More sharing options...
Weganator Posted April 27, 2011 Share Posted April 27, 2011 Why wouldn't the cost of the floor be 12x*12y? 12 dollars per square feet. x feet * y feet = xy square feet If it were 12 dollars per foot, it would be 12x * 12y Link to comment Share on other sites More sharing options...
Chiefinonhaze Posted April 27, 2011 Author Share Posted April 27, 2011 C(x,y,z) = 12xy+20xz+20yz+14xy How confident are you in this answer? I'm putting this for my Homework in Calc 3 if your 100% confident. I know the problem should be easy, but I keep messing up. Link to comment Share on other sites More sharing options...
Slacky McSlackAss Posted April 27, 2011 Share Posted April 27, 2011 Because the room is in rectangular fashion, the walls will cost different amounts. I stand by my answer of C(x,y,z) = 12xy+20xz+20yz+14xy Link to comment Share on other sites More sharing options...
Weganator Posted April 27, 2011 Share Posted April 27, 2011 How confident are you in this answer? I'm putting this for my Homework in Calc 3 if your 100% confident. I know the problem should be easy, but I keep messing up. Thats it... its the same answer i had, mine is simplified... thats it.. Break the problem down into its parts... solve each part.. and combine them... Link to comment Share on other sites More sharing options...
Slacky McSlackAss Posted April 27, 2011 Share Posted April 27, 2011 How confident are you in this answer? I'm putting this for my Homework in Calc 3 if your 100% confident. I know the problem should be easy, but I keep messing up. I'm fairly confident that it's right. ---------- Post added April-26th-2011 at 09:24 PM ---------- Thats it... its the same answer i had, mine is simplified... thats it..Break the problem down into its parts... solve each part.. and combine them... Yep!!! BTW, another CS student here. CS FTW!!! Link to comment Share on other sites More sharing options...
Chiefinonhaze Posted April 27, 2011 Author Share Posted April 27, 2011 Because the room is in rectangular fashion, the walls will cost different amounts. I stand by my answer of C(x,y,z) = 12xy+20xz+20yz+14xy I'm not ready to type in into the response box yet. It's due thursday, and I want a definitive response before I type in my last chance. It really doesn't matter if I get this question right, and I could care less. I just want to see if anyone on Extremeskins can answer an upper level college math question correctly Because apparently I can't. Link to comment Share on other sites More sharing options...
SonOfWashington Posted April 27, 2011 Share Posted April 27, 2011 Apparently you aren't the first to ask this question. http://storagebuildingplan.info/17/storage-building-plans-costs-2/ Link to comment Share on other sites More sharing options...
Slacky McSlackAss Posted April 27, 2011 Share Posted April 27, 2011 I'm not ready to type in into the response box yet. It's due thursday, and I want a definitive response before I type in my last chance.It really doesn't matter if I get this question right, and I could care less. I just want to see if anyone on Extremeskins can answer an upper level college math question correctly Because apparently I can't. Yeah, I hear ya. Should be interesting to see some of the answers that ES gets. This is a bit more complex than the PEMDAS problem from last time. Link to comment Share on other sites More sharing options...
SonOfWashington Posted April 27, 2011 Share Posted April 27, 2011 I'm thinking C(x,y,z) = 12(xy) + 10(2xz) +10(2yz) + 14(xy) = 26xy + 20xz + 20yz Link to comment Share on other sites More sharing options...
Weganator Posted April 27, 2011 Share Posted April 27, 2011 I'm thinkingC(x,y,z) = 12(xy) + 10(2xz) +10(2yz) + 14(xy) = 12xy + 20xz + 20yz + 14xy = 26xy + 20xz + 20yz Be fearless man.. thats 3 of us now!! You got it... I'm off for a bit... Good Luck!!! Link to comment Share on other sites More sharing options...
SonOfWashington Posted April 27, 2011 Share Posted April 27, 2011 Did you just start calc 3 OP? I'm in calc 3 too and I remember doing this at the start of the semester. Link to comment Share on other sites More sharing options...
Beans Posted April 27, 2011 Share Posted April 27, 2011 I'm putting this for my Homework in Calc 3 This seems more like a College Algebra problem. I'm pretty sure that Weganator has the correct answer. the problem describes a box (flat sides, flat top, flat bottom), so the solution is to simply find the area of the 6 rectangles using the associated cost and x,y,z, then describe the total surface area as a function of those 3 variables. Easy peazy. Link to comment Share on other sites More sharing options...
SonOfWashington Posted April 27, 2011 Share Posted April 27, 2011 This seems more like a College Algebra problem. I'm pretty sure that Weganator has the correct answer. the problem describes a box (flat sides, flat top, flat bottom), so the solution is to simply find the area of the 6 rectangles using the associated cost and x,y,z, then describe the total surface area as a function of those 3 variables. Easy peazy. Calc 3 is all about multivariable functions. They're touched on in lower classes though. Link to comment Share on other sites More sharing options...
Beans Posted April 27, 2011 Share Posted April 27, 2011 Calc 3 is all about multivariable functions. They're touched on in lower classes though. True. What till he gets to integration and differentiation of spherical coordinates. This forum is gonna be flooded with math problems. Link to comment Share on other sites More sharing options...
SonOfWashington Posted April 27, 2011 Share Posted April 27, 2011 True. What till he gets to integration and differentiation of spherical coordinates. This forum is gonna be flooded with math problems. My exam is on Monday. Spherical and cylindrical coordinates are my 2nd least favorite part of this class, behind 3D surfaces.I love ES math threads. Link to comment Share on other sites More sharing options...
Chiefinonhaze Posted April 27, 2011 Author Share Posted April 27, 2011 Yeah this is a refresher in multivariable functions. I really don't know why I got this question wrong when I submitted it the first two times. I got a different answer than others though. Link to comment Share on other sites More sharing options...
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