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  1. M

    general form of lines and circles in complex plane

    Prove the equation of a line and a circle in complex plane has a general form of : \alpha \ z\overline{z}+\beta \ z + \overline{\beta\ z}+ \gamma = 0 where \alpha,\gamma \in \mathbb{R}, \beta \in \mathbb{C} Hence, or otherwise, prove If z,z_{1},z_{2} are complex numbers which...
  2. M

    inequality and sides of triangles

    If alb,c are sides a triangle, then prove 3(ab+bc+ca) \leq (a+b+c)^{2} \leq 4(ab+bc+ca)
  3. M

    Finding limit of S

    Let S_{n} = \frac{5}{9} \ \frac{14}{20} \ \frac{27}{35} \ ... \ \frac{2n^{2}-n-1}{2n^{2}+n-1} then find \lim_{n\to\infty}S_{n}
  4. M

    Trig equation

    Prove for n\geq 2 tan(\alpha) \ tan(2\alpha)+ tan(2\alpha) \ tan(3\alpha)+ ...+ tan((n-1)\alpha) \ tan(n\alpha) = \frac{tan(n\alpha)}{tan(\alpha)}-n
  5. M

    Inequality question

    If 0< x <\frac{\pi}{2} prove sin(x) > x - \frac{x^{3}}{4}
  6. M

    limit question

    Suppose A= 2^{n}\underbrace{\sqrt{2-\sqrt{2+\sqrt{2+...+\sqrt{2+2cos\alpha}}}}}_{n \ times} then simplify A in terms of n and \alpha , then find lim_{n\to\infty}A
  7. M

    log question

    If log_{a}16 + log_{\sqrt{2}}a = 9 then find a.
  8. M

    Finding Polynomial

    Suppose P(x) is a polynomial which satisfies the following condition: P(P'(x)) = 27x^{6}-27x^{4}+6x^{2}+2. find a possible polynomial, P(x), that satisfies the above condition.
  9. M

    Arithmetic sequence

    Suppose a_{1},a_{2},...,a_{n} is an arithmetic sequence.Then prove \frac{1}{\sqrt{a_{1}}+\sqrt{a_{2}}}+\frac{1}{\sqrt{a_{2}}+\sqrt{a_{3}}}+...+\frac{1}{\sqrt{a_{n-1}}+\sqrt{a_{n}}} =\frac{n-1}{\sqrt{a_{1}}+\sqrt{a_{n}}}
  10. M

    Trig question and its limit

    This is the question: let P = (1-tan^{2}\frac{a}{2})(1-tan^{2}\frac{a}{2^{2}}) (1-tan^{2}\frac{a}{2^{3}})...(1-tan^{2}\frac{a}{2^{m}}) and by simplifying P, find lim_{m\to\infty}P
  11. M

    HSC 2017-2018 Maths Marathon

    Re: HSC 2017 Maths (Advanced) Marathon To solve it in a different way, we can look at the roots, since x^{3}-8 is a cubic polynomial then there are three roots, \alpha, \beta, \gamma .Obviously one of the roots is 2,so let \alpha = 2 then sum and product of the roots imply \beta+...
  12. M

    HSC 2017 MX1 Marathon

    The solution is correct. But your solution is exactly the same as the other one: In the textbook's solution, they subtracted two angles one at a time, meaning: \angle ABC = 180 - \angle ACB - \angle CBA But you subtracted the sum in one go, meaning: \angle ABC = 180 - (\angle ACB + \angle CBA)
  13. M

    HSC 2017 MX1 Marathon

    a) 1 < m \leq \frac{\pi}{2} because sin^{-1}x is an odd function. So to find all possible lines we have to make sure that it passes through the origin, which it always does, and one point on the first quadrant (x,y). and by oddness of sin^{-1}x , the line also passes through (-x,-y) as...
  14. M

    4u trig proof

    I thought to share another method to tackle the question: \frac{1}{4}+ \frac{3}{4}cos^{2}2x = \frac{1}{4}+ \frac{3}{4}(1-sin^{2}2x) = 1 -3sin^{2}x \ cos^{2}x = 1-3sin^{2}x \ cos^{2}x \ (sin^{2}x \ + cos^{2}x) = 1-3sin^{4}x\ cos^{2}x -3sin^{2}x \ cos^{4}x = sin^{6}x \ +cos^{6}x The last...
  15. M

    My first assessments sucked :(

    I have experienced that in physics. I came second in the first test but in the second exam/assessment I made a huge mistake which made me come 22nd out 40 in my cohort.I was determined to close the gap and in the next exam I came in the 10th place. Finally by coming 1st in my trial, I achieved...
  16. M

    Complex number Q

    Another slightly different method is to multiply the original equation by (1-i) then equation only the imaginary parts yields: -5y=-10 and equating the real part of the original part shows x = 4
  17. M

    Simple complex number question

    Expanding on that idea, we can prove in a different way why \sqrt{-6 } \sqrt{-6} = 6 is not correct. let f(x) be our extended square root function, principal square root, where (f(-1))^{2} = -1, the definition of i,. we want to prove any function with that condition can not satisfy f(x)f(y)...
  18. M

    Polynomial Topic Questions

    A different method is to play with sum and product of the roots. let p(x) = ax^{4}+bx^{3}+x^{2}+4x+2 then from the info in the question we know p(x)-(2x+3) is divisible by Q(x)= 2x^{2}+2x-1 Note the roots of Q(x) are \frac{-1\pm \sqrt{3}}{2} let's called the other two \alpha ...
  19. M

    Help pls

    the answers are correct, as far as I can tell, but this is a proper proof: after 1 year: owed money= (20000-3000)*1.06 after 2 years: owed money= ( (20000-3000)*1.06 -3000)*1.06 = 20000*1.06^{2} - 3000*(1.06+1.06^{2}) . . . . after n years: owed money = 20000*1.06^{n} -...
  20. M

    3u Integration Question

    Thank you for pointing that out, I fixed it.
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