1. **State the problem:** Find the equations of the tangent lines to the curve given by $$x^4y^2 + x^2y^4 = 26x^6 - 6$$ at $$x=1$$.
2. **Implicit differentiation:** Differentiate both sides with respect to $$x$$. Use the product rule and chain rule where necessary.
Given: $$x^4y^2 + x^2y^4 = 26x^6 - 6$$
Differentiate term by term:
$$\frac{d}{dx}(x^4y^2) + \frac{d}{dx}(x^2y^4) = \frac{d}{dx}(26x^6 - 6)$$
For $$x^4y^2$$:
$$\frac{d}{dx}(x^4y^2) = 4x^3y^2 + x^4 \cdot 2y \frac{dy}{dx} = 4x^3y^2 + 2x^4y \frac{dy}{dx}$$
For $$x^2y^4$$:
$$\frac{d}{dx}(x^2y^4) = 2xy^4 + x^2 \cdot 4y^3 \frac{dy}{dx} = 2xy^4 + 4x^2y^3 \frac{dy}{dx}$$
Right side:
$$\frac{d}{dx}(26x^6 - 6) = 156x^5$$
3. **Combine derivatives:**
$$4x^3y^2 + 2x^4y \frac{dy}{dx} + 2xy^4 + 4x^2y^3 \frac{dy}{dx} = 156x^5$$
Group $$\frac{dy}{dx}$$ terms:
$$2x^4y \frac{dy}{dx} + 4x^2y^3 \frac{dy}{dx} = 156x^5 - 4x^3y^2 - 2xy^4$$
Factor $$\frac{dy}{dx}$$:
$$\frac{dy}{dx}(2x^4y + 4x^2y^3) = 156x^5 - 4x^3y^2 - 2xy^4$$
4. **Solve for $$\frac{dy}{dx}$$:**
$$\frac{dy}{dx} = \frac{156x^5 - 4x^3y^2 - 2xy^4}{2x^4y + 4x^2y^3}$$
5. **Evaluate at $$x=1$$:**
First find $$y$$ values at $$x=1$$ by substituting into original equation:
$$1^4 y^2 + 1^2 y^4 = 26(1)^6 - 6$$
$$y^2 + y^4 = 20$$
Rewrite as:
$$y^4 + y^2 - 20 = 0$$
Let $$z = y^2$$, then:
$$z^2 + z - 20 = 0$$
Solve quadratic:
$$z = \frac{-1 \pm \sqrt{1 + 80}}{2} = \frac{-1 \pm 9}{2}$$
Possible $$z$$ values:
$$z = 4$$ or $$z = -5$$ (discard negative since $$y^2 \geq 0$$)
So $$y^2 = 4 \Rightarrow y = \pm 2$$
6. **Calculate slopes at points (1,2) and (1,-2):**
For $$y=2$$:
$$\frac{dy}{dx} = \frac{156(1)^5 - 4(1)^3(2)^2 - 2(1)(2)^4}{2(1)^4(2) + 4(1)^2(2)^3} = \frac{156 - 16 - 32}{4 + 32} = \frac{108}{36} = 3$$
For $$y=-2$$:
$$\frac{dy}{dx} = \frac{156 - 4(1)(-2)^2 - 2(1)(-2)^4}{2(1)(-2) + 4(1)(-2)^3} = \frac{156 - 16 - 32}{-4 - 32} = \frac{108}{-36} = -3$$
7. **Write tangent line equations:**
Use point-slope form $$y - y_1 = m(x - x_1)$$ with $$x_1=1$$.
For $$y=2$$ and slope $$3$$:
$$y - 2 = 3(x - 1) \Rightarrow y = 3x - 3 + 2 = 3x - 1$$
For $$y=-2$$ and slope $$-3$$:
$$y + 2 = -3(x - 1) \Rightarrow y = -3x + 3 - 2 = -3x + 1$$
**Final answer:** The tangent lines at $$x=1$$ are:
$$y = 3x - 1$$
and
$$y = -3x + 1$$
Tangent Lines Ad315C
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