Maxito Posted September 24, 2005 Share Posted September 24, 2005 I am having difficulty with this math problem 9x(3x-5)^2 + 3(3x-5)^3 I been getting different answers for this question is 18x2 + 3x+35 the right answer 2 means squared X is a variable Link to comment Share on other sites More sharing options...
mhd24 Posted September 24, 2005 Share Posted September 24, 2005 The answer is -36*225 (Don't have a calculator on me mate. I assume x means multiplication and is not a variable. 9x(3x-5)^2 + 3(3x-5)^3 is: 9*(-15^2)+(3*-15^3) which is: 225*(9-(3*15)) which is: 225*-36 (* is multiplication) Link to comment Share on other sites More sharing options...
Maxito Posted September 24, 2005 Author Share Posted September 24, 2005 X is a variable. My mistake should of made it a little bit more clear Link to comment Share on other sites More sharing options...
iheartskins Posted September 24, 2005 Share Posted September 24, 2005 Paging Ignatius J and DjTj... Link to comment Share on other sites More sharing options...
Skins4SB Posted September 24, 2005 Share Posted September 24, 2005 I got the following: (162x^3)-(432x^2)+(900x)-375 It probably can be factored but I'm too lazy for that now... But it looks like I'm way off the answer. I forgot what method you can use for the cube. Link to comment Share on other sites More sharing options...
Chopper Dave Posted September 24, 2005 Share Posted September 24, 2005 I got the following:(162x^3)-(432x^2)+(900x)-375 It probably can be factored but I'm too lazy for that now... But it looks like I'm way off the answer. I forgot what method you can use for the cube. That's what I got, too. It's got to be the right answer. It's not that difficult of a problem, the numbers are just fairly large. Link to comment Share on other sites More sharing options...
Mooka Posted September 24, 2005 Share Posted September 24, 2005 the answer is: 162 * (X - 5/3)^2 * (X - 5/6) Link to comment Share on other sites More sharing options...
jrockster21 Posted September 24, 2005 Share Posted September 24, 2005 I am having difficulty with this math problem9x(3x-5)^2 + 3(3x-5)^3 I been getting different answers for this question is 18x2 + 3x+35 the right answer 2 means squared X is a variable What is the problem? Do you have to expand? Its not an equation, so you can't be solving for x. What is it you are trying to do, exactly? Link to comment Share on other sites More sharing options...
Ignatius J. Posted September 24, 2005 Share Posted September 24, 2005 yeah i'm not sure what the question is. Link to comment Share on other sites More sharing options...
PokerPacker Posted September 24, 2005 Share Posted September 24, 2005 9x(3x-5)(3x-5)+3(3x-5)(3x-5)(3x-5) 9x(9x^2-30x+25)+3(9x^2-30x+25)(3x-5) 81x^3-270x^2+225x+3(27x^3-45x^2-90x^2+150x+75x-125) 81x^3-270x^2+225x+81x^3-135x^2-270x^2+450x+225x-375 162x^3-675x^2+900x-375 3(54x^3-225x^2+300x-125) Link to comment Share on other sites More sharing options...
TheSteve Posted September 24, 2005 Share Posted September 24, 2005 ^There's a possibility that it can still be factored down Link to comment Share on other sites More sharing options...
Thiebear Posted September 24, 2005 Share Posted September 24, 2005 Were you asked to simplify it or evaluate it? All of the above is simplification. Evaluating or solving it would be -8100 or thats what i read at Dr. math and Google. Link to comment Share on other sites More sharing options...
Maxito Posted September 24, 2005 Author Share Posted September 24, 2005 What is the problem? Do you have to expand? Its not an equation, so you can't be solving for x. What is it you are trying to do, exactly? All the instruction tells me is to Factor completely. Link to comment Share on other sites More sharing options...
chomerics Posted September 24, 2005 Share Posted September 24, 2005 Poker Packer has the right answer. There needs to be a cube because of the ^3rd power in the second half of the problem, so the initial answer you thought was right is incorrect. I am not sure if it can be broken down and factored any more. According to this factor calculator, it can not http://www.algebrahelp.com/calculators/expression/factoring/ Link to comment Share on other sites More sharing options...
Maxito Posted September 24, 2005 Author Share Posted September 24, 2005 thanks for the help Link to comment Share on other sites More sharing options...
The Sir Posted September 24, 2005 Share Posted September 24, 2005 I got 162x^3-675x^2+1575x-750 I believe some above got this and factored a 3 out of it, not sure if there's a bigger number that can be factored out. Link to comment Share on other sites More sharing options...
DjTj Posted September 24, 2005 Share Posted September 24, 2005 Paging Ignatius J and DjTj... 9x(3x-5)^2 + 3(3x-5)^3 9x(9x^2-30x+25) + 3(27x^3-135x^2+225x-125) 81x^3-270x^2+225x + 81x^3-405x^2+675x-375 162x^3 - 675x^2 + 900x - 375 ...That's the same as what PokerPacker got - you can factor out a 3 like he did also. Usually when math problems come out like this, I check to make sure I didn't copy the problem out of the book wrong, and then I just get pissed at the teacher for assigning such a ridiculous problem. Link to comment Share on other sites More sharing options...
chomerics Posted September 24, 2005 Share Posted September 24, 2005 Usually when math problems come out like this, I check to make sure I didn't copy the problem out of the book wrong, and then I just get pissed at the teacher for assigning such a ridiculous problem. I agree, this does nothing except frustrates students. Link to comment Share on other sites More sharing options...
BlueTalon Posted September 24, 2005 Share Posted September 24, 2005 I'm not familiar with the "^" symbol. Is that keyboard shorthand for "to the power of..." ? Link to comment Share on other sites More sharing options...
mhd24 Posted September 24, 2005 Share Posted September 24, 2005 I'm not familiar with the "^" symbol. Is that keyboard shorthand for "to the power of..." ? ^ is exponent. Link to comment Share on other sites More sharing options...
mrdoctor Posted September 24, 2005 Share Posted September 24, 2005 162*x^3-675*x^2+900*x-375 Link to comment Share on other sites More sharing options...
Maxito Posted September 24, 2005 Author Share Posted September 24, 2005 Thanks again everybody. I appreciate the help. Link to comment Share on other sites More sharing options...
Mooka Posted September 24, 2005 Share Posted September 24, 2005 Poker Packer has the right answer. There needs to be a cube because of the ^3rd power in the second half of the problem, so the initial answer you thought was right is incorrect.I am not sure if it can be broken down and factored any more. According to this factor calculator, it can not http://www.algebrahelp.com/calculators/expression/factoring/ It can but not into nice integers. The roots of the cubic function are 5/3 and 5/6. You have to graph the function and find the roots. 5/6 is one root. The graph curves and meets at 5/3 so (X-5/3)^2 is the other 2. You can use synthetic division if you want but its easier to see that the whole thing is multiplied by 54. (54X^3 - 225X^2 + 300X - 125) So you have: 3 * 54 * (X - 5/3)^2 * (X - 5/6) Link to comment Share on other sites More sharing options...
TheSteve Posted September 24, 2005 Share Posted September 24, 2005 That's what I thought mooka. I was just too lazy to do the synthetic division and I didn't have a calculator nearby. Link to comment Share on other sites More sharing options...
Cdowwe Posted September 24, 2005 Share Posted September 24, 2005 Ahh good ole math Link to comment Share on other sites More sharing options...
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