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y=arccos(-(x)/(5))
Evaluate 
(dy)/(dx) at 
x=2.
Use an exact expression.

y=arccos(x5) y=\arccos \left(-\frac{x}{5}\right) \newlineEvaluate dydx \frac{d y}{d x} at x=2 x=2 .\newlineUse an exact expression.

Full solution

Q. y=arccos(x5) y=\arccos \left(-\frac{x}{5}\right) \newlineEvaluate dydx \frac{d y}{d x} at x=2 x=2 .\newlineUse an exact expression.
  1. Find Derivative of y=arccos(x5):</b>First,letsfindthederivativeof$y=arccos(x5)y=\arccos\left(-\frac{x}{5}\right):</b> First, let's find the derivative of \$y=\arccos\left(-\frac{x}{5}\right). Using the chain rule, the derivative of arccos(u)\arccos(u) is 11u2-\frac{1}{\sqrt{1-u^2}} times the derivative of uu.
  2. Apply Chain Rule: Let u=x5u=-\frac{x}{5}. Then, dudx=15\frac{du}{dx} = -\frac{1}{5}.
  3. Plug in uu and Simplify: Now, plug uu into the derivative of arccos(u)\arccos(u) to get dydx=11(x5)2(15)\frac{dy}{dx} = -\frac{1}{\sqrt{1-\left(-\frac{x}{5}\right)^2}} \cdot \left(-\frac{1}{5}\right).
  4. Evaluate at x=2x=2: Simplify the expression: dydx=11(x225)(15)\frac{dy}{dx} = -\frac{1}{\sqrt{1-\left(\frac{x^2}{25}\right)}} \cdot \left(-\frac{1}{5}\right).
  5. Calculate Inside Square Root: Now, evaluate dydx\frac{dy}{dx} at x=2x=2. Plug x=2x=2 into the derivative: dydx=11(2225)×(15)\frac{dy}{dx} = -\frac{1}{\sqrt{1-\left(\frac{2^2}{25}\right)}} \times \left(-\frac{1}{5}\right).
  6. Take Square Root: Calculate the inside of the square root: 1(22)/(25)=1(4)/(25)=14/25=21/251-(2^2)/(25) = 1-(4)/(25) = 1-4/25 = 21/25.
  7. Multiply by 15-\frac{1}{5}: Now, take the square root: 2125=215\sqrt{\frac{21}{25}} = \frac{\sqrt{21}}{5}.
  8. Multiply by 15-\frac{1}{5}: Now, take the square root: 2125=215\sqrt{\frac{21}{25}} = \frac{\sqrt{21}}{5}.Finally, multiply by 15-\frac{1}{5}: dydx=121/5×(15)=1521/5=121\frac{dy}{dx} = -\frac{1}{\sqrt{21}/5} \times (-\frac{1}{5}) = \frac{1}{5\sqrt{21}/5} = \frac{1}{\sqrt{21}}.

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