jasignhagj Posted February 27, 2011 Share Posted February 27, 2011 So here's what I have I get lost after the second step, I believe he said to make a perfect square, and then factor into a(x-h)^2+k Link to comment Share on other sites More sharing options...
Retech Posted February 27, 2011 Share Posted February 27, 2011 Right, you have the more difficult part already. So now we have... A = -2w^2 + 40w Now notice that in a parabola, the maximum (for a downward facing parabola) or the minimum (upward facing parabola) has the x-coordinate as the axis of symmetry. The axis of symmetry can be found by using the following formula: -b/2a The a and b come from the standard form of the quadratic expression Y-coordinate = ax^2 + bx + c In the first equation, the a is -2 and the b is 40. Thusly, the axis of symmetry is -40/2(-2) = 10. Therefore, the x coordinate of the maximum is 10. We can use this to find the y coordinate (which is what you need to solve the problem) by plugging in the x coordinate into all instances of x (which is w, in this case). A = -2(10)^2 + 40 (10)A = -200 + 400A = 200 I'm unsure if you learned these things or whether I should go ahead with your teacher's way, but your teacher has probaly made this much harder than it needs to be. Master of your domain? I am Lord of the manor, Queen of the castle, King of the county! Former moderator of the original DungeoneeringFormer moderator of Ye Olde HegemonyModerator of the remake of DungeoneeringFormer Empress of the Lichten Empire (Hegemony)Former President of the United States (Hegemony)Former Emporer of Imperial Japan (Hegemony)Czarina Catherine of Imperial Russia (Hegemony The only difference between a disagreement between friends, an argument between strangers, and a feud between enemies is the ability to reconcile. Link to comment Share on other sites More sharing options...
The_Mather1 Posted February 27, 2011 Share Posted February 27, 2011 I can't find way to get the exact numbers (they don't exist), but we can get as close as:W = 0,00001L = 39,99998A = 0,0004That may look ok, but it's because at that point excel gives up on exact decimals, as you can see, A is slightly off. Twitter: @TheMather1 Link to comment Share on other sites More sharing options...
Retech Posted February 27, 2011 Share Posted February 27, 2011 I can't find way to get the exact numbers (they don't exist), but we can get as close as:W = 0,00001L = 39,99998A = 0,0004That may look ok, but it's because at that point excel gives up on exact decimals, as you can see, A is slightly off. Firstly, it's totally inaccurate. Secondly, Spork needs an algebraic way of solving it for his class. Thirdly, there are exact numbers for them. Master of your domain? I am Lord of the manor, Queen of the castle, King of the county! Former moderator of the original DungeoneeringFormer moderator of Ye Olde HegemonyModerator of the remake of DungeoneeringFormer Empress of the Lichten Empire (Hegemony)Former President of the United States (Hegemony)Former Emporer of Imperial Japan (Hegemony)Czarina Catherine of Imperial Russia (Hegemony The only difference between a disagreement between friends, an argument between strangers, and a feud between enemies is the ability to reconcile. Link to comment Share on other sites More sharing options...
Jehosaphat Posted February 27, 2011 Share Posted February 27, 2011 Right, you have the more difficult part already. So now we have... A = -2w^2 + 40w Now notice that in a parabola, the maximum (for a downward facing parabola) or the minimum (upward facing parabola) has the x-coordinate as the axis of symmetry. The axis of symmetry can be found by using the following formula: -b/2a The a and b come from the standard form of the quadratic expression Y-coordinate = ax^2 + bx + c In the first equation, the a is -2 and the b is 40. Thusly, the axis of symmetry is -40/2(-2) = 10. Therefore, the x coordinate of the maximum is 10. We can use this to find the y coordinate (which is what you need to solve the problem) by plugging in the x coordinate into all instances of x (which is w, in this case). A = -2(10)^2 + 40 (10)A = -200 + 400A = 200 I'm unsure if you learned these things or whether I should go ahead with your teacher's way, but your teacher has probaly made this much harder than it needs to be.Oh, the good ol' -b/2a trick. Forgot about that. IT'S EASIER WITH CALCULUS Link to comment Share on other sites More sharing options...
Retech Posted February 27, 2011 Share Posted February 27, 2011 NO IT ISN'T INTEGRATION AND CURVE SKETCHING DOESN'T SOLVE EVERYTHING Master of your domain? I am Lord of the manor, Queen of the castle, King of the county! Former moderator of the original DungeoneeringFormer moderator of Ye Olde HegemonyModerator of the remake of DungeoneeringFormer Empress of the Lichten Empire (Hegemony)Former President of the United States (Hegemony)Former Emporer of Imperial Japan (Hegemony)Czarina Catherine of Imperial Russia (Hegemony The only difference between a disagreement between friends, an argument between strangers, and a feud between enemies is the ability to reconcile. Link to comment Share on other sites More sharing options...
The_Mather1 Posted February 27, 2011 Share Posted February 27, 2011 If you go through my numbers then you'll se that they go perfectly along with the rules stated in the picture. I used the rules for A according to W and used smaller and smaller numbers for W until the A values according to those rules matched. W= 0,00001A= (40+(A8*2))*A8 A= (A8*40)-((2*A8)^2) P= 40W= 0,00001L= F5-(2*F6)A= F6*F7 My excel sheet with the equals removed. Twitter: @TheMather1 Link to comment Share on other sites More sharing options...
archimage_a Posted February 27, 2011 Share Posted February 27, 2011 Errr Graphs are considerably easier... http://www.uzzisoft..../archimage.jpegWell I knew you wouldn't agree. I know how you hate facing facts. Link to comment Share on other sites More sharing options...
Jehosaphat Posted February 27, 2011 Share Posted February 27, 2011 NO IT ISN'T INTEGRATION AND CURVE SKETCHING DOESN'T SOLVE EVERYTHINGActually, this one's derivative calculus. Maxes and mins have a derivative of zero. So:A=-2x^2+40xA'=-4x+40=0-4x=-40x=10 And I only wrote all that out to "show my work". Normally, I'd just look at it and do the derivative and algebra in my head. Link to comment Share on other sites More sharing options...
Retech Posted February 27, 2011 Share Posted February 27, 2011 1. Graphs are somewhat inaccurate, but the whole point of the max/min was figuring out the graph. 2. Stork, you basically did what I did, but cheated because calculus isn't allowed in geometry class. Master of your domain? I am Lord of the manor, Queen of the castle, King of the county! Former moderator of the original DungeoneeringFormer moderator of Ye Olde HegemonyModerator of the remake of DungeoneeringFormer Empress of the Lichten Empire (Hegemony)Former President of the United States (Hegemony)Former Emporer of Imperial Japan (Hegemony)Czarina Catherine of Imperial Russia (Hegemony The only difference between a disagreement between friends, an argument between strangers, and a feud between enemies is the ability to reconcile. Link to comment Share on other sites More sharing options...
Resistance Posted February 27, 2011 Share Posted February 27, 2011 So, I might be choosing a signiture soon. What do you guys think? Link to comment Share on other sites More sharing options...
Retech Posted February 27, 2011 Share Posted February 27, 2011 Kewl. Master of your domain? I am Lord of the manor, Queen of the castle, King of the county! Former moderator of the original DungeoneeringFormer moderator of Ye Olde HegemonyModerator of the remake of DungeoneeringFormer Empress of the Lichten Empire (Hegemony)Former President of the United States (Hegemony)Former Emporer of Imperial Japan (Hegemony)Czarina Catherine of Imperial Russia (Hegemony The only difference between a disagreement between friends, an argument between strangers, and a feud between enemies is the ability to reconcile. Link to comment Share on other sites More sharing options...
Resistance Posted February 27, 2011 Share Posted February 27, 2011 Any suggestions though :P. Link to comment Share on other sites More sharing options...
Jehosaphat Posted February 27, 2011 Share Posted February 27, 2011 2. Stork, you basically did what I did, but cheated because calculus isn't allowed in geometry class.But... but... I LIKE calculus... Now if it were a trig problem, I'd say "screw it, you're on your own." Trig is evil. Link to comment Share on other sites More sharing options...
Retech Posted February 27, 2011 Share Posted February 27, 2011 Trig is great. Messing around with the identities for a few minutes while the clock is ticking on the tests is the definition of a rollercoaster ride. Master of your domain? I am Lord of the manor, Queen of the castle, King of the county! Former moderator of the original DungeoneeringFormer moderator of Ye Olde HegemonyModerator of the remake of DungeoneeringFormer Empress of the Lichten Empire (Hegemony)Former President of the United States (Hegemony)Former Emporer of Imperial Japan (Hegemony)Czarina Catherine of Imperial Russia (Hegemony The only difference between a disagreement between friends, an argument between strangers, and a feud between enemies is the ability to reconcile. Link to comment Share on other sites More sharing options...
The_Mather1 Posted February 27, 2011 Share Posted February 27, 2011 Trig sucks, sadly it is used in several aspects of electrics, so I have to use it a lot. But luckily it is only used in multi-fase currents and I'll be rid of it next year in electronics. Twitter: @TheMather1 Link to comment Share on other sites More sharing options...
Seraphi Posted February 27, 2011 Share Posted February 27, 2011 I hate trigonometry, which is part of the reason I am not so great at vectors. Link to comment Share on other sites More sharing options...
Jehosaphat Posted February 28, 2011 Share Posted February 28, 2011 I hate trigonometry, which is part of the reason I am not so great at vectors.Vector trig is easier than calculus trig. I mean, it's just sine and cosine relative to your coordinate plane, as far as I've learned. Calculus trig gets annoying because you have to chain-rule the trig functions. And if you're already doing the chain rule once or twice, it gets really easy to screw up. Link to comment Share on other sites More sharing options...
The_Mather1 Posted February 28, 2011 Share Posted February 28, 2011 Sin, Cos, Tan, Sin-1, Cos-1 and Tan-1 to calculate the sides and agles of a 90° triangle according to eachother. It's hell no matter how you use it. And you will only need it in architecture and AC motors, yet we still have to learn it. Twitter: @TheMather1 Link to comment Share on other sites More sharing options...
Resistance Posted February 28, 2011 Share Posted February 28, 2011 Well I love trigonometry, its just a set of rules that you follow. Nothing too hard, no actual brain work. Link to comment Share on other sites More sharing options...
archimage_a Posted February 28, 2011 Share Posted February 28, 2011 Mathmatics is basically following a set of rules to a desired outcome...hence why computers can do it far better than humans. The only area Humans excel over computers is deciding which set of rules to use. http://www.uzzisoft..../archimage.jpegWell I knew you wouldn't agree. I know how you hate facing facts. Link to comment Share on other sites More sharing options...
Nero Posted February 28, 2011 Share Posted February 28, 2011 [bleep] math. Vienna Raszyn Warsaw Klushino Link to comment Share on other sites More sharing options...
The_Mather1 Posted February 28, 2011 Share Posted February 28, 2011 No there's no brain work, because it is impossible without a calculator or computer, and I mean literally impossible. Twitter: @TheMather1 Link to comment Share on other sites More sharing options...
The Dark Lord Posted February 28, 2011 Share Posted February 28, 2011 [bleep] math. This. A million [bleep]ing times. Seriously, [bleep] math. And I'm having to take remedial algebra because my high school teachers sucked (except my Algebra I teacher, but I took his class in 8th grade and forgot a lot of what I learned). :wall: SWAG Mayn U wanna be like me but U can't be me cuz U ain't got ma swagga on. Link to comment Share on other sites More sharing options...
Alg Posted February 28, 2011 Share Posted February 28, 2011 [bleep] math. This. A million [bleep]ing times. Seriously, [bleep] math.Indeed. I painted some stuff and put it on tumblr Link to comment Share on other sites More sharing options...
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