Search results

  1. J

    identity qn

    So it is true for x = -a. Is it true for all real x? Use algebraic manipulation to simplify the left side to x. bc(a+x)/[(a-b)(a-c)] + ...... = -bc(a+x)(b-c)/[(a-b)(b-c)(c-a)] + ........ etc :) :) :wave:
  2. J

    identity qn

    First a = 2, b = -3 and c = -5 OR a = -2, b = 3 and c = 5 :) :) :wave:
  3. J

    Root of unity

    Because 1 + w + w^2 = 0, .: 1 + w = -w^2 :) :) :wave:
  4. J

    help.. 2 questions

    If the first equation has real roots, its discriminant >= 0, .: a^2 - b^2 >= 0 , assuming a =/= b (note: I think this is given), then a^2 - b^2 > 0 and the discriminant of the second equation < 0, .: the second equation has unreal roots. If the first equation has unreal roots, its...
  5. J

    help.. 2 questions

    Please type your question carefully. Is the first equation 8(a^2)x(2x-1)+b^2=0 ? :) :) :wave:
  6. J

    Polynomial questions

    Given that P(x) = 2x^3 + x^2 - 4x - 2 has a rational zero, instead of using the factor theorem, factorise by grouping the terms appropriately (not always possible) to find the rational zero(s). P(x) = 2x^3 + x^2 - 4x - 2 = (2x^3 + x^2) - (4x + 2) = x^2 ( 2x + 1) - 2(2x + 1) = (2x + 1)(x^2 -...
  7. J

    Inertial reference question

    Not true. There are many ways to detect the motion of the coin from the plane, e.g. you can see the coin becoming smaller as it moves away from you. :) :) :wave:
  8. J

    Equation of a curve question

    y=ax^(2n) implies (0,0). Use (-60,18) and (40,8) to set up simul. eqs. 18 = a(-60)^(2n) 8 = a(40)^(2n) 18/8 = (-60/40)^(2n), simplify to 9/4 = (-3/2)^(2n) 9/4 = (9/4)^n .: n = 1 Sub. into 8 = a(40)^(2n) to find a = 1/200 :) :) :wave:
  9. J

    Inertial reference question

    In this case, as the coin travels straight down from your POV you can't tell what state of motion you are in. Only from an outside observer's POV where they saw the parabolic trajectory of the coin can it be said that the plane is moving. The above atatement did not explain why the plane was...
  10. J

    yr 11 revision - questions

    |x+1|/(x^2 - 1) = |x+1|/[(x-1)(x+1)] is defined for all x values except -1 and 1. To simplify the expression, consider the two cases: x < -1 and x > -1. For x < -1, |x+1|/(x^2 - 1) = 1/(1-x) For x > -1, |x+1|/(x^2 - 1) = 1/(x-1). This second case covers x =0, |x+1|/(x^2 - 1) =...
  11. J

    Need help in Series Application; Superannuation!

    You did not type the formula correctly! :) :) :wave:
  12. J

    need help !! volume question

    You have left out the minus and dx. :) :) :wave:
  13. J

    yr 11 revision - questions

    when |x +1| <0 .......... This is wrong. | | is always greater than or equal to 0, and since x =/= -1, so |x + 1|>0. For x < -1, |x + 1|/[(x - 1)(x + 1)] = -(x +1)/[(x - 1)(x + 1)] = -1/(x - 1)...
  14. J

    factor theorem

    Quote 'Correct. Strictly speaking, equations have solutions, while polynomials have roots.' Happy 2006 + 1 :) :) :wave: <!-- google_ad_section_end -->
  15. J

    Need help in Series Application; Superannuation!

    Dash's investment after 6 years: A = PR^n = 9000(1 + 8/100)^6 =$14281.87 Happy 2006 + 1 :) :) :wave:
  16. J

    Need help in Series Application; Superannuation!

    P is the initial amount invested. In this question P = 0. Q is amount invested at the end of each year. Superannuation formula. Happy 2007 :) :) :wave:
  17. J

    Geom. Applications of Calc.

    The equation is correct. dA/dx = 1/2[-x^2 /sqrt(25 - x^2) + sqrt(25 - x^2)] = 0 x^2 = 25/2 so max area = 1/2 (5/sqrt2)(5/sqrt2) = 6.25 Happy 2007 :) :) :wave:
  18. J

    Need help in Series Application; Superannuation!

    Use A = PR^n + Q(R^n - 1)/(R - 1) to calculate the savings. P = 0, Q = 2000, R = 1 + r/100 = 1.075, n = 5 A = 11616.78 The balance = 15000 - 11616.78 = $3383.22 :) :) :wave:
  19. J

    factor theorem

    Prove that the polynomial P(x) = 5x^4 + 2x^3 - 3x^2 - x + 3 does not have integer roots. Possible integer roots are +/- 1, +/- 3. P(+/- 1) =/= 0, P(+/- 3) =/= 0, no integer roots. zeros of a polynomial and roots of a polynomial are the same. Prove that P(x).... cannot have...
  20. J

    factor theorem

    Yes, e.g. p(x) = x^2 +3x/2 +1/2, p(-1) = 0, p(-1/2) = 0. q(x) = 2x^2 + 3x + 1, q(-1) = 0, q(-1/2) = 0. q(x) = 2p(x) Note: The factor theorem is used mainly to find rational factors. There are infinite number of polynomials with irrational factors. :) :) :wave:
Top