Math Problem Statement

Verify that the given point lies on the curve. Evaluate x^3 + y^3 for x = 3 and y = 3. Determine an equation of the line tangent to the curve at the given point.

Solution

The given problem requires us to:

a. Verify that the point (3, 3) lies on the curve defined by the equation:

x3+y3=6xyx^3 + y^3 = 6xy We need to evaluate the expression x3+y3x^3 + y^3 at x=3x = 3 and y=3y = 3 to check if the point satisfies the equation.

b. Find the equation of the tangent line to the curve at the given point (3, 3).

To do this, we will use implicit differentiation to find the slope of the tangent at that point.

Let me first tackle part (a).

Part (a) - Verify the point (3, 3) on the curve:

We need to substitute x=3x = 3 and y=3y = 3 into the equation:

x3+y3=6xyx^3 + y^3 = 6xy

Substitute x=3x = 3 and y=3y = 3: 33+33=6(3)(3)3^3 + 3^3 = 6(3)(3) 27+27=5427 + 27 = 54 54=5454 = 54 Thus, the point (3, 3) does lie on the curve, as both sides of the equation are equal.

Part (b) - Find the equation of the tangent line:

To find the equation of the tangent line at the point (3, 3), we need to differentiate the equation x3+y3=6xyx^3 + y^3 = 6xy implicitly with respect to xx.

Differentiating both sides with respect to xx:

  • The derivative of x3x^3 with respect to xx is 3x23x^2.
  • The derivative of y3y^3 with respect to xx is 3y2dydx3y^2 \frac{dy}{dx} (using the chain rule).
  • The derivative of 6xy6xy with respect to xx is 6y+6xdydx6y + 6x \frac{dy}{dx} (using the product rule).

So, the differentiated equation is: 3x2+3y2dydx=6y+6xdydx3x^2 + 3y^2 \frac{dy}{dx} = 6y + 6x \frac{dy}{dx}

Now, solve for dydx\frac{dy}{dx} (the slope of the tangent):

3y2dydx6xdydx=6y3x23y^2 \frac{dy}{dx} - 6x \frac{dy}{dx} = 6y - 3x^2 Factor out dydx\frac{dy}{dx} on the left side: dydx(3y26x)=6y3x2\frac{dy}{dx} (3y^2 - 6x) = 6y - 3x^2 dydx=6y3x23y26x\frac{dy}{dx} = \frac{6y - 3x^2}{3y^2 - 6x}

Now, substitute x=3x = 3 and y=3y = 3 into this derivative to find the slope at the point (3, 3): dydx=6(3)3(32)3(32)6(3)\frac{dy}{dx} = \frac{6(3) - 3(3^2)}{3(3^2) - 6(3)} dydx=18272718\frac{dy}{dx} = \frac{18 - 27}{27 - 18} dydx=99=1\frac{dy}{dx} = \frac{-9}{9} = -1

So, the slope of the tangent line at (3, 3) is 1-1.

Finally, we can write the equation of the tangent line using the point-slope form: yy1=m(xx1)y - y_1 = m(x - x_1) Substituting m=1m = -1, x1=3x_1 = 3, and y1=3y_1 = 3: y3=1(x3)y - 3 = -1(x - 3) Simplify this equation: y3=x+3y - 3 = -x + 3 y=x+6y = -x + 6

Thus, the equation of the tangent line is: y=x+6y = -x + 6

Would you like more details or any further explanations on these steps? Here are some related questions:

  1. How do we apply implicit differentiation in more complex equations?
  2. Can you explain the point-slope form of a line further?
  3. How do we verify that other points lie on a curve in general?
  4. Can we apply the same method to find the equation of the tangent line to a curve defined in polar coordinates?
  5. What is the significance of the slope in the context of real-world problems?

Tip: Implicit differentiation is very useful when you have equations where both variables xx and yy are mixed together, and you need to find the derivative with respect to one variable.

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Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Tangents to Curves
Curve Analysis

Formulas

x^3 + y^3 = 6xy
dy/dx = (6y - 3x^2) / (3y^2 - 6x)
Point-slope form of a line: y - y1 = m(x - x1)

Theorems

Implicit Differentiation Theorem
Point-Slope Form of a Line

Suitable Grade Level

Grades 11-12