Posted: 4/10/2009 8:21:06 AM EDT
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Guys, I am taking introductary alagabra. Its an online class so I am not learing anthing. I have read over my book twice so far and I am still stuck on a few questions. The first is this z(cubed)-125/z-5 I can only come up with 2z(squared)+5z-25. Its a multiple choice question and my answer doesnt fit. I am lost. I know I am dumb but can someone explain to me how to get the right answer? |
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Quoted:
Guys, I am taking introductary alagabra. Its an online class so I am not learing anthing. I have read over my book twice so far and I am still stuck on a few questions. The first is this z(cubed)-125/z-5 I can only come up with 2z(squared)+5z-25. Its a multiple choice question and my answer doesnt fit. I am lost. I know I am dumb but can someone explain to me how to get the right answer? I don't understand the question are you supposed to solve for Z? Or are you supposed to just simplify? and where is the = and the other side of the equation?? (Also, on computers the exponent is written as follows 23^2 <–––– that means 23 "squared". X^3 <––- that means X "cubed" There are many ways to "atttack" an algebra problem. I hate it when there is a Fraction with a variable so id mulitply that to both sides. |
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Quoted: Quoted: Guys, I am taking introductary alagabra. Its an online class so I am not learing anthing. I have read over my book twice so far and I am still stuck on a few questions. The first is this z(cubed)-125/z-5 I can only come up with 2z(squared)+5z-25. Its a multiple choice question and my answer doesnt fit. I am lost. I know I am dumb but can someone explain to me how to get the right answer? I don't understand the question are you supposed to solve for Z? Or are you supposed to just simplify? and where is the = and the other side of the equation?? (Also, on computers the exponent is written as follows 23^2 <–––– that means 23 "squared". X^3 <––- that means X "cubed" There are many ways to "atttack" an algebra problem. I hate it when there is a Fraction with a variable so id mulitply that to both sides. Simplify. Ok here it is again z^3-125/z-5 I understand how to get the z^2 and 25 but where does the 5z come from? |
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Quoted: Quoted: z2 + 5z + 25 This. Use synthetic division. 1 0 0 -125 5 5 25 125 1 5 25 (0) = z2 + 5z + 25 God I havent seen that in so long. I dont even remember how to use it. Luckily my poly sci degree only requires 2 math classes and this is one of them. I plan on retaking this class later this year in an actual classroom. I cant learn shit doing these online classes. |
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Quoted: Ok but how did you get to that? I am stuck on the beginning. I am getting so irritated and disheartened because of this. I will never use shit like this so why in the hell do i need to know how to do it? How about teaching personal finance.z2 + 5z + 25 ( a3 - b3 ) = ( a - b ) * ( a2 + ab + b2 ) ( z3 - 125) = ( z - 5 ) * (z2 + 5z + 25 ) ( z - 5 ) * (z2 + 5z + 25 ) _____________________ = (z2 + 5z + 25 ) ( z - 5) |
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Ok but how did you get to that? I am stuck on the beginning. I am getting so irritated and disheartened because of this. I will never use shit like this so why in the hell do i need to know how to do it? How about teaching personal finance.
z2 + 5z + 25 ( a3 - b3 ) = ( a - b ) * ( a2 + ab + b2 ) ( z3 - 125) = ( z - 5 ) * (z2 + 5z + 25 ) ( z - 5 ) * (z2 + 5z + 25 ) _____________________ = (z2 + 5z + 25 ) ( z - 5)
That is the formula for factoring the difference of two cubes - you just memorize it and use it whenever you need it. I always hated memorization, so I try to find methods that will yield the correct result without plugging in numbers to a formula. In this case, you are dividing a 3rd degree polynomial by a 1st degree polynomial, and synthetic division is the quickest method. |
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OK, i assume you mean that the other side means X so it goes as follows––––
Z^3 - Z125 / Z- 5 = X Solve for X Get rid of that fucking Denomiator by multiplying both side by Z-5 that gives you (Z^3 - Z125) = X (Z-5) Z^3 - Z125 = X(Z-5) <–––––– that is the answer. If you want to simplify it more you factor out the Z^3-Z125. To Simplify Z^3 - Z125 you take out the Z So that leaves you Z (Z^2 - 125) |
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Quoted: Quoted: Ok but how did you get to that? I am stuck on the beginning. I am getting so irritated and disheartened because of this. I will never use shit like this so why in the hell do i need to know how to do it? How about teaching personal finance.z2 + 5z + 25 ( a3 - b3 ) = ( a - b ) * ( a2 + ab + b2 ) ( z3 - 125) = ( z - 5 ) * (z2 + 5z + 25 ) ( z - 5 ) * (z2 + 5z + 25 ) _____________________ = (z2 + 5z + 25 ) ( z - 5) Sorry, I'm not sure how to break it down any simpler without going into a proof of why ( a3 - b3 ) = ( a - b ) * ( a2 + ab + b2 ) which is definitely not a beginner Algebra lesson. |
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z2 + 5z + 25 ( a3 - b3 ) = ( a - b ) * ( a2 + ab + b2 ) ( z3 - 125) = ( z - 5 ) * (z2 + 5z + 25 ) ( z - 5 ) * (z2 + 5z + 25 ) _____________________ = (z2 + 5z + 25 ) ( z - 5)
Difference of two cubes over z-5, FOIL the top , cancel the denomitaor and bingo Z^2+5Z+25 |
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Quoted: Quoted: Quoted: Z^3 - 125 is (Z-5)^3 so (Z-5)^3 / z-5 simplifies to (z-5)^2 Nope. Yes. -5^3 is -125 all day long. Of course, but ( z - 5 )3 is equal to ( z3 - 15z2 + 75z - 125 ). Look at it this way: plug a random # in for z, lets use 7. So you are saying that ( 73 - 125 ) is equal to (7 - 5)3 . ( 73 - 125 ) = 218 ( 7 - 5 )3 = 8 |
| Was there a text book assigned for your class? If not, buy a solutions manual for a similar class. I used this method to get through several algebra/statistics classes. I ended up buying solutions manuals from amazon.com for classes that were similar to mine. They show how to go through each problem step by step, just find a problem that is similar to yours. There are also many online free math tutor sites. Good Luck. |
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Quoted: Was there a text book assigned for your class? If not, buy a solutions manual for a similar class. I used this method to get through several algebra/statistics classes. I ended up buying solutions manuals from amazon.com for classes that were similar to mine. They show how to go through each problem step by step, just find a problem that is similar to yours. There are also many online free math tutor sites. Good Luck. Yes I have a book but it doesnt explain enough for me to understand. This is why I cannot take online math classes. I need to sit in a classroom so my teacher can show me how dumb I really am. |
Looks like you've got difference of squares licked. Study up more on difference of cubes and you should do fine.|
Quoted: Was there a text book assigned for your class? If not, buy a solutions manual for a similar class. I used this method to get through several algebra/statistics classes. I ended up buying solutions manuals from amazon.com for classes that were similar to mine. They show how to go through each problem step by step, just find a problem that is similar to yours. There are also many online free math tutor sites. Good Luck. Is this what you are talking about? http://www.amazon.com/Student-Solutions-manual-Introductory-Algebra/dp/0321285808/ref=sr_1_15?ie=UTF8&qid=1239384871&sr=8-15 |
None of those choices are right.
| Thanks to everyone who helped me. Those questions were from quiz 4 and I still had to do quiz 3. After your help with quiz 4, quiz 3 was easy. I am now just reading up on Negative Exponents and Scientific Notation, Exponents and operations on polynomials, and dividing polynomials, the same crap you helped me with. I have to post 1 answer only from 1 of the 3 sections. That is why I dont learn anything here. Not enough homework. |
 To the OP, I almost forgot the order of operations until you posted this, and I used to love algebra. Haven't had a class in 6 year's though. Jeremy ETA : The reason as to why I love Algebra is, because that's the basis for Chemistry and I love chemistry. |
