Recent content by liquidwater

  1. L

    Use '3 sin x - 4(sin x)^3' to show that if sin x = sin (3x), then sin x = 0 or

    Alright, thank you very much!
  2. L

    Use '3 sin x - 4(sin x)^3' to show that if sin x = sin (3x), then sin x = 0 or

    "Eliminate" sin3x from sin(3x) = 3 sin x - 4 sin^3 x? Sorry for not understanding but I'm really lost :(. Do I solve sin(x) = 3 sin x - 4 sin^3 x?And how does sin x = sin 3x when sin(1) isn't equal to sin(3)
  3. L

    Use '3 sin x - 4(sin x)^3' to show that if sin x = sin (3x), then sin x = 0 or

    The three equations I wrote are totally different aren't they... one is y = sin(3x), another y = sin(x) and the other y = 0. (where y is the same equation). I think I misunderstood your first post.
  4. L

    Use '3 sin x - 4(sin x)^3' to show that if sin x = sin (3x), then sin x = 0 or

    Solve -4 sin ^3 x + 3 sin x = sin 3x and -4 sin ^3 x + 3 sin x = sin x ? edit: or Solve -4 sin ^3 3x + 3 sin 3x = 0 ?
  5. L

    Use '3 sin x - 4(sin x)^3' to show that if sin x = sin (3x), then sin x = 0 or

    Use '3 sin x - 4(sin x)^3' to show that if sin x = sin (3x), then sin x = 0 or... Homework Statement Use double-angle and addition formulæ and other relations for trigonometrical functions to find an expression for sin(3x) in terms of sin x alone. Use the expression you have found to show...
  6. L

    Finding an expression for (e.g. sin (3x)) in terms of (e.g. sin x) alone?

    Thanks a lot to both of you, I actually understand what is required now. I'm a bit lost with actually getting the solution, but I really do need to work on my math skills so I'll do that. Thanks again!
  7. L

    Finding an expression for (e.g. sin (3x)) in terms of (e.g. sin x) alone?

    Homework Statement Use double-angle and addition formulæ and other relations for trigonometrical functions to find an expression for sin(3x) in terms of sin x alone. My problem is I don't know what is meant by "find an expression for sin(3x) in terms of sin x alone.". I know the relevant...
  8. L

    Finding x-intercept of cubic functions? / Factoring cubic functions

    :approve: Thanks a lot! I'll start working on this stuff.
  9. L

    Finding x-intercept of cubic functions? / Factoring cubic functions

    Thanks... I can't factorize cubic functions, I should have explicitly asked for help with that. Should I be able to this kind of thing in my head, just by looking at it? Or is there some sort of formulae/tricks that I can use? I can factorize quadratics fine (but I often just turn to quadratic...
  10. L

    Finding x-intercept of cubic functions? / Factoring cubic functions

    Thanks for replying, That's what I'm really having trouble with... "With quadratic functions I usually use the quadratic formula. I try to figure out how to factor these equations in my head but I can rarely get it right." I can't think of the right combination of numbers to use.
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    Finding x-intercept of cubic functions? / Factoring cubic functions

    Homework Statement My problem is that whenever I have to use cubic functions - whether it's finding the roots (when dy/dx kis a cubic function) or finding the x-intercepts... With quadratic functions I usually use the quadratic formula. I try to figure out how to factor these equations in my...