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  1. C

    Some confusions about Commerce/Science - Actuarial Studies + Maths + Stats

    "The Level 1 and 2 Mathematics and Statistics courses are compulsory (bit see below on MATH2931) and the others are strongly recommended. MATH1151/1251 replace MATH1131/1231 in the formal requirements for a Mathematics or Statistics major. MATH2901 and MATH2931 are required for Part I exemption...
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    Complex

    check the question... should it be (x+1)^2 instead of (x^2+1)^2 Btw is x a real number? If so.... think modulus
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    Com/Sci textbooks

    ACCT1501 - Prescribed Textbook only... dunno about practice set. ECON1101 - Prescribed Textbook only MATH1151 - Don't buy Salas. It's not needed in first year nor second year maths. The course notes (not shown on textlist but is required) are sufficient. Dunno about MGMT
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    Imaginay Nos

    Um not quite right Z=1/(z-3)+17/3 does not imply |Z|=|1/(z-3)|+17/3.... think triangle inequality... rather Z-17/3=1/(z-3) --->|Z-17/3|=1/3 Explanation: Instead of considering z, consider the complex number m=1/(z-3). |z-3|=3 implies |1/(z-3)|=1/3, which implies |m|=1/3, so it means...
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    Imaginay Nos

    actually i think you are right but you just got confused The locus of 1/(z-3) was a circle of same centre so 1/(z-3) + 17/3 equals to a locus of (x-17/3)^2+y^2=1/9. (51/9=17/3) This is because every point 1/(z-3) on the circle shifts right by 17/3, so logically the centre of the circle should...
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    Imaginay Nos

    Close but not quite.... cos adding 3+i onto the vector 2z should move it upwards by i and right by 3, so logically the centre of the circle should shift by the same amount Or convert into parametrics question: Let P=z=x+iy so x^2+y^2=k^2 (x,y,X,Y are real) Let Q=X+iY such that Q=2z+3+i...
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    4 Unit Revising Marathon HSC '10

    This part requires you assume z=cosx+isinx which assumes |z|=1 Rather: ((z+1)/(z-1))^n=-1 Taking mod from both sides gives: |z+1|^n/|z-1|^n=1 |z+1|/|z-1|=1 |z+1|=|z-1| Solving for z geometrically implies z is purely imaginary or 0, and hence can be expressed as z=ia where a is real.
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    Asymptote : re- curve sketching

    It is perfectly clear what OP is asking for. The graph can be rearranged into a hyperbola: x^2 - 4y^2 = 4 --> x^2/4 - y^2 = 1 noting asymptotes of a hyperbola (of the form x^2/a^2-y^2/b^2=1) is y=bx/a and y=-bx/a then the asymptotes are y=x/2 and y=-x/2.
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    Complex Locus

    arg(2)=0 btw..... so that doesnt work (division via 0) |z-2|=2 doesnt imply z-2=2 or -2.... z-2 could be 1+sqrt(3)i An algebraic solution would be |z-2|=2 --> z-2=2cisx for some x (ie arg(z-2)=x) z=2(cosx+1+isinx) Note cosx+1=2cos^2(x/2) and sinx=2cos(x/2)sin(x/2) z=2(2cos(x/2))cis(x/2) after...
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    What is a good double degree for Actuarial Studies?

    I do actuarial/maths/stats: Non actuarial commerce courses (aka acct+econ): Just do homework.... rest can be crammed b4 assessments. So on avg around 1-2 hours Actuarial commerce courses: Homework+readings+re-reading lecture notes until material is completely understood.... so avg 4-5...
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    Commerce/Science timetable

    Lmao discrete maths with 4 lectures on 4 days... happens every year
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    Actuarial/Law

    Not at UNSW.
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    Quick Complex Numbers Q

    I think you got the question wrong. It should be (1-cosx-isinx)/(1+cosx+isinx) (test x=pi/2 to see the original is incorrect) So you should get: tan(x/2)(sin(x/2)-icos(x/2))/(cos(x/2)+isin(x/2)) =tan(x/2)(cos(pi/2-x/2)-isin(pi/2-x/2))/cis(x/2) noting cos(x)=cos(-x) and -sin(x)=sin(-x)...
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    De Moivre's Theorem

    w^3=1 ==> (w-1)(w^2+w+1)=0 But w is not real so w=/=1 so w^2+w+1=0 and hence w=-w^2-1
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    complex stuff

    Modulus method (a+ib)^2=-12-16i |(a+ib)^2|=|-12-16i| noting |z^2|=|z|^2 |a+ib|^2=sqrt(144+256) noting |a+ib|=sqrt(a^2+b^2) a^2+b^2=20 Then combine with a^2-b^2 to get the answer
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    Complex Number Question

    x^2=(16-8t^2+t^4)/(4+t^2)^2 y^2=16t^2/(4+t^2)^2 x^2+y^2=(16-8t^2+t^4)/(4+t^2)^2+16t^2/(4+t^2)^2 = (16+8t^2+t^4)/(4+t^2)^2 = (4+t^2)^2/(4+t^2)^2=1
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    Complex Number Question

    Make the denominator real: z=(2+it)^2/[(2+it)(2-it)]=(4-t^2+4it)/(4+t^2) Let z=x+iy x=Re(z)=(4-t^2)/(4+t^2) y=Im(z)=4t/(4+t^2) The rest just involves some parametrics work in 3u to get rid of t (hint square x and y and then combine) You should get x^2+y^2=1 i think
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    Complex Locus

    The vector z-a is the vector from the complex number a to the complex number z IN THE DIRECTION TOWARDS a. The problem with the solutions is that they mistaken the direction of the vector. z-i is going FROM i TO P, while the argument they have shown is for the vector going from P to i, which...
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    Complex Locus

    I agree. A more rigorous solution would be: arg(z-i) - arg(z+i) = pi/2 let z=x+iy , x,y are real arg((z-i)/(z+i))=pi/2 arg((x+iy-i)/(x+iy+i)=pi/2 arg((x^2+y^2-1-2ix)/denominator (dont care))=pi/2 ==> real part =0 and imaginary part >0 we also note the denominator (after making it real)...
  20. C

    Complex Locus

    arctan((-2x)/(x^2 + y^2 -1)) = pi/2 ==> denominator=0 AND numerator is positive as tan(pi/2) is +infinity So -2x>0 and x^2+y^2=1 So x<0 and x^2+y^2=1
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