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Calc Problem - find dy/dt when y^2 = x^2 + 1?

Y^2 = x^2 + 1

dx/dt = 500

find dy/dt when x = 2

4 Answers

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  • Anonymous
    10 years ago
    Favorite Answer

    x=2 ---> y = ...

    and y(dy/dt) = x(dx/dt) ----> dy/dt = .,.

  • QC
    Lv 7
    10 years ago

    First we find dy/dx using implicit differentiation:

    2y dy/dx = 2x

    dy/dx = x/y

    When x = 2

    y^2 = 2^2 + 1 = 5

    y = ± √5

    Using chain rule:

    dy/dt = dy/dx * dx/dt

    dy/dt = x/y dx/dt

    dy/dt = 2/± √5 * 500

    dy/dt = ± 1000/√5 = ± 200√5

    NOTE: It's not possible to know if dy/dt = 200√5 or -200√5 without more information.

    Mαthmφm

  • 10 years ago

    y² = x² + 1

    2y(dy/dt) = 2x(dx/dt) + 0

    Solve for y first:

    y² = 2² + 1

    y = ±√5

    ±2√5(dy/dt) = 2(2)(500)

    dy/dt = ±1000/√5 ≈ ±447.214

  • 10 years ago

    2y(dy/dt) = 2x(dx/dt)

    dy/dt = x/y * (dx/dt)

    When x = 2, y = +/- √5

    dy/dt when x = 2: +/- 2/√5 * (500)

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