Find the equation of the tangent line to the curve y^5 = x^3 - y at the point (2, √2).

Question image

Understand the Problem

The question is asking to find the equation of the tangent line to a given curve at a specified point. This will involve differentiating the curve equation to find the slope at that point and then using the point-slope form of the line equation.

Answer

The equation of the tangent line is $$ y = \frac{4}{7}x - \frac{8}{7} + \sqrt{2}. $$
Answer for screen readers

The equation of the tangent line is

$$ y = \frac{4}{7}x - \frac{8}{7} + \sqrt{2}. $$

Steps to Solve

  1. Differentiate the curve equation

Start with the curve equation given:

$$ y^5 = x^3 - y. $$

Differentiate both sides with respect to $x$. Using implicit differentiation, we get:

$$ 5y^4 \frac{dy}{dx} = 3x^2 - \frac{dy}{dx}. $$

  1. Isolate $\frac{dy}{dx}$

Rearranging the equation to solve for $\frac{dy}{dx}$:

$$ 5y^4 \frac{dy}{dx} + \frac{dy}{dx} = 3x^2 $$

This simplifies to:

$$ (5y^4 + 1) \frac{dy}{dx} = 3x^2 $$

Hence,

$$ \frac{dy}{dx} = \frac{3x^2}{5y^4 + 1}. $$

  1. Substitute the point into the equation

Now, substitute the coordinates of the point $(2, \sqrt{2})$ into the derivative to find the slope of the tangent:

$$ \frac{dy}{dx} = \frac{3(2)^2}{5(\sqrt{2})^4 + 1} $$

Calculating this gives:

$$ (2)^2 = 4; \quad (\sqrt{2})^4 = 4 $$

So,

$$ \frac{dy}{dx} = \frac{3 \cdot 4}{5 \cdot 4 + 1} = \frac{12}{20 + 1} = \frac{12}{21} = \frac{4}{7}. $$

  1. Use point-slope form to find the tangent line

Now using the point-slope form of the line equation, which is:

$$ y - y_1 = m(x - x_1), $$

where $m = \frac{4}{7}$, $x_1 = 2$, and $y_1 = \sqrt{2}$:

$$ y - \sqrt{2} = \frac{4}{7}(x - 2). $$

  1. Rearranging to get the equation of the tangent line

Distributing and rearranging gives:

$$ y = \frac{4}{7}x - \frac{8}{7} + \sqrt{2}. $$

This can be left in this form as the equation of the tangent line.

The equation of the tangent line is

$$ y = \frac{4}{7}x - \frac{8}{7} + \sqrt{2}. $$

More Information

The tangent line provides the best linear approximation to the curve at the specified point. This technique is fundamental in calculus, helping to analyze the behavior of functions.

Tips

  • Forgetting to use implicit differentiation: Ensure to apply implicit differentiation properly to both sides of the equation.
  • Not simplifying fractions correctly: Double-check calculations when simplifying fractions.

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