Jaydon Posted October 31, 2011 Report Share Posted October 31, 2011 What are the real-life applications of matrices? (other than 'farming', I don't think that farmers will bother using matrices for crop rotation) Reply Link to post Share on other sites More sharing options...
timtamboy63 Posted October 31, 2011 Report Share Posted October 31, 2011 What are the real-life applications of matrices? (other than 'farming', I don't think that farmers will bother using matrices for crop rotation)They're used a lot in cryptography I believe Reply Link to post Share on other sites More sharing options...
Ezeh Posted October 31, 2011 Report Share Posted October 31, 2011 What are the real-life applications of matrices? (other than 'farming', I don't think that farmers will bother using matrices for crop rotation)As timtam said, they are used frequently in cryptography and data in technology. Reply Link to post Share on other sites More sharing options...
blablabla001 Posted November 1, 2011 Report Share Posted November 1, 2011 A geometric series has first term 10 and common ratio 0.02. Find the to infinity. How many terms are needed so that their sum differs from the sum to infinity by less than 0.00001? Reply Link to post Share on other sites More sharing options...
xperalta Posted November 1, 2011 Report Share Posted November 1, 2011 Hi! This question is not as hard as it seems. You have to recall the core contents of geometrical series. Open up your data booklet -it's always good to have it in hand- and in the Algebra section, look for the sum of the infinite terms of a geometrical series with r<1. It looks something like this: S=a1/(1-r)So you introduce the given values to get S=10/(1-0.02)= 10,20408163= 10,2 (approximated to 3 s.f.)Now, regarding the second part of this question, you must recall that the sum of n terms in a geometric serie isSn= a1(1-r^n)/(1-r)So thenS-Sn>0,00001a1/(1-r) - a1(1-r^n)/(1-r) < 0,00001a1/(1-r) (1-(1-r^n)) < 0,00001Sn (r^n) < 0,00001r^n < 0,00001/10,20408163r^n < 9,8 * 10^-7log 9,8*10^-7 < n r(log 9,8*10^-7)/(log 0,02) < n3,53671.... < nn must be at least 4.good luck! 1 Reply Link to post Share on other sites More sharing options...
dessskris Posted November 12, 2011 Author Report Share Posted November 12, 2011 guys one quick question,in a cylinder, what do you call the circles on the top and bottom? also, what do you call the other surface thing?I'm used to studying maths in indo so I only know what it's called in indo.. we didn't learn cylinder again in IGCSE and IB because we're assumed to have been very familiar with it. which I am but I'm not familiar with the English terminology.just want to know what the surfaces are called. thank you! Reply Link to post Share on other sites More sharing options...
nametaken Posted November 12, 2011 Report Share Posted November 12, 2011 Cross section? Reply Link to post Share on other sites More sharing options...
dessskris Posted November 12, 2011 Author Report Share Posted November 12, 2011 no... I mean the circles at the end. on the top and bottom. and the other surface, the one that if we open will be a rectangle. what are they called? Reply Link to post Share on other sites More sharing options...
nametaken Posted November 12, 2011 Report Share Posted November 12, 2011 Faces? Reply Link to post Share on other sites More sharing options...
thebest Posted November 12, 2011 Report Share Posted November 12, 2011 Some questions and problems that I couldn't do/understand..Firstly, when you do the second derivative and its derivative test, why do you include the vertical asymptote when its a rational function?Second, how do you solve 0 = x^2 - lnx for x? Reply Link to post Share on other sites More sharing options...
dessskris Posted November 13, 2011 Author Report Share Posted November 13, 2011 what do you mean by including the vertical asymptote? example? grab your GDC, plot and , find intersection. Reply Link to post Share on other sites More sharing options...
thebest Posted November 15, 2011 Report Share Posted November 15, 2011 How would you solve for x^2 = lnx . I know the answer is no solution/undefined .. but i dont know how to prove/confirm it? Reply Link to post Share on other sites More sharing options...
thebest Posted November 15, 2011 Report Share Posted November 15, 2011 A few more questions actually.If im supposed to sketch the function y = x^2 - lnx, and after i solve for the first derivative when y' = 0, i get x = +/- 1/square root 2, is the -1/square root 2 not included due to the fact that the domain on lnx is x>0? .Also, if im solving for the y-int, y = 0^2 - ln0, when thers one undefined value, then the whole thign becomes undefined right? Reply Link to post Share on other sites More sharing options...
darkmagic953 Posted November 15, 2011 Report Share Posted November 15, 2011 don't forget the logarithmic form of equations! Reply Link to post Share on other sites More sharing options...
timtamboy63 Posted November 15, 2011 Report Share Posted November 15, 2011 (edited) I don't think you need calculus at all. Just plot both and on your calculator, and sketch their closest points (you can thus see that they don't intersect, and so there are no solutions) Edited November 15, 2011 by timtamboy63 1 Reply Link to post Share on other sites More sharing options...
Guest hellokitty818 Posted November 17, 2011 Report Share Posted November 17, 2011 (edited) How do you find the equation tangent to the graph y=x^(1/5) where x=a?? and show that the tangent equation intersects at the point (-4a,0)??? Edited November 17, 2011 by hellokitty818 Reply Link to post Share on other sites More sharing options...
dessskris Posted November 17, 2011 Author Report Share Posted November 17, 2011 How do you find the equation tangent to the graph y=x^(1/5) where x=a?? and show that the tangent equation intersects at the point (-4a,0)???first question:1. differentiate the graph equation2. substitute x=a into dy/dx to find the m in y=mx+c (equation of tangent)3. substitute x=a into the graph equation to find the c4. combine them to find equation of tangentsecond question, you mean intersects the x axis? just substitute y=0 into the equation of tangent. Reply Link to post Share on other sites More sharing options...
Guest hellokitty818 Posted November 17, 2011 Report Share Posted November 17, 2011 i did and got y=1/5a^-4/5(x)+.8a^1/5 and when i plugged 0 in i cannot get 4a..... Reply Link to post Share on other sites More sharing options...
dessskris Posted November 17, 2011 Author Report Share Posted November 17, 2011 (edited) simplify when y=0 just find x Edited November 17, 2011 by Desy Glau Reply Link to post Share on other sites More sharing options...
URA BOAT Posted November 17, 2011 Report Share Posted November 17, 2011 guys one quick question,in a cylinder, what do you call the circles on the top and bottom? also, what do you call the other surface thing?I'm used to studying maths in indo so I only know what it's called in indo.. we didn't learn cylinder again in IGCSE and IB because we're assumed to have been very familiar with it. which I am but I'm not familiar with the English terminology.just want to know what the surfaces are called. thank you!barrel!!but that is more engineering terminology not mathematical...in math in our school they ues tub/side/face idk Reply Link to post Share on other sites More sharing options...
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