nid help to slove these questions

• ZaiDancerz

  7 Mar 10, 17:10

  1.)          The tangent to the curve y=px^3 at the point where x =2 passes through the point (1,-10). Find the value of p.

  2.) The period, T seconds of a pendulum is given by T= 2*pie*square root (l over g) where l is the length of the pendulum and g is the acceleration due to gravity. If g is a constant ,find dT/dl .

   

• wee_ws

  7 Mar 10, 19:19

  Hi,

    For Q1:

    1. When x = 2, y = ?

    2. dy/dx = ?

    3. When x = 2, value of dy/dx = ?

    4. Gradient of line joining the point where x = 2 and (1, -10) = ?

    5. Now value of dy/dx = gradient of line, from which p = ?

    For Q2:

    1. Rewrite T as T = {2 pi (g)^-0.5} (l)^0.5, noting that the expression within braces is a constant.

    2. Use the fact that the derivative of x^n is nx^(n-1), to find dT/dl.

    Thanks.

  Cheers,
  Wen Shih

• ZaiDancerz

  7 Mar 10, 21:34

  so the ans for question1 is 2.5?

• TrueHeart

  7 Mar 10, 21:59

  Originally posted by ZaiDancerz:

  so the ans for question1 is 2.5?

  Hi ZaiDancerz,

  That is correct.

  Cheers.

• wee_ws

  8 Mar 10, 14:29

  Hi ZaiDancerz,

    Getting acquainted with the problem-solving steps is important. Thanks.

  Cheers,
  Wen Shih