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curve is defined by the parametric equations 
x(t)=7e^(-8t) and 
y(t)=-7sin(-10 t). Find 
(dy)/(dx).

A curve is defined by the parametric equations x(t)=7e8tx(t) = 7e^{-8t} and y(t)=7sin(10t)y(t) = -7\sin(-10t). Find dydx\frac{dy}{dx}.

Full solution

Q. A curve is defined by the parametric equations x(t)=7e8tx(t) = 7e^{-8t} and y(t)=7sin(10t)y(t) = -7\sin(-10t). Find dydx\frac{dy}{dx}.
  1. Find dxdt\frac{dx}{dt}: To find dydx\frac{dy}{dx} for parametric equations, we need to find dydt\frac{dy}{dt} and dxdt\frac{dx}{dt} separately and then divide dydt\frac{dy}{dt} by dxdt\frac{dx}{dt}.
  2. Find dydt\frac{dy}{dt}: First, let's find dxdt\frac{dx}{dt}, which is the derivative of xx with respect to tt.
    dxdt=ddt[7e(8t)]\frac{dx}{dt} = \frac{d}{dt} [7e^{(-8t)}]
    Using the chain rule, we get:
    dxdt=7(8)e(8t)\frac{dx}{dt} = 7 \cdot (-8) \cdot e^{(-8t)}
    dxdt=56e(8t)\frac{dx}{dt} = -56e^{(-8t)}
  3. Calculate dydx\frac{dy}{dx}: Next, we find dydt\frac{dy}{dt}, which is the derivative of yy with respect to tt.
    dydt=ddt[7sin(10t)]\frac{dy}{dt} = \frac{d}{dt} [-7\sin(-10t)]
    Using the chain rule, we get:
    dydt=7×(10)×cos(10t)\frac{dy}{dt} = -7 \times (-10) \times \cos(-10t)
    dydt=70cos(10t)\frac{dy}{dt} = 70\cos(-10t)
    Since cosine is an even function, cos(10t)=cos(10t)\cos(-10t) = \cos(10t), so we can simplify to:
    dydt=70cos(10t)\frac{dy}{dt} = 70\cos(10t)
  4. Simplify expression: Now we have both derivatives:\newlinedxdt=56e8t\frac{dx}{dt} = -56e^{-8t}\newlinedydt=70cos(10t)\frac{dy}{dt} = 70\cos(10t)\newlineTo find dydx\frac{dy}{dx}, we divide dydt\frac{dy}{dt} by dxdt\frac{dx}{dt}:\newlinedydx=dydtdxdt\frac{dy}{dx} = \frac{\frac{dy}{dt}}{\frac{dx}{dt}}\newlinedydx=70cos(10t)56e8t\frac{dy}{dx} = \frac{70\cos(10t)}{-56e^{-8t}}
  5. Final (dydx)(\frac{dy}{dx}) expression: We can simplify the expression by dividing both the numerator and the denominator by 77:(dydx)=10cos(10t)8e8t(\frac{dy}{dx}) = \frac{10\cos(10t)}{-8e^{-8t}}
  6. Final (dydx)(\frac{dy}{dx}) expression: We can simplify the expression by dividing both the numerator and the denominator by 77:
    (dydx)=10cos(10t)8e8t(\frac{dy}{dx}) = \frac{10\cos(10t)}{-8e^{-8t}}Finally, we can write the simplified expression for (dydx)(\frac{dy}{dx}):
    (dydx)=10cos(10t)8e8t(\frac{dy}{dx}) = -\frac{10\cos(10t)}{8e^{-8t}}

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