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  1. $x^2+xy+y^2=7$
  2. Find $dy/dx$
  3. $dy/dx= (-2x-y)/(x+2y)$

How do I take $dy/dx$ and get the equation of the tangent line parallel to the $x$-axis?

  • 0
    What's your question, specifically?2012-09-28
  • 2
    Combine (1) with $\frac{dy}{dx} = 0$ from (3). If you have done it correctly, you get two lines, since (1) gives an ellipse centered at the origin.2012-09-28
  • 1
    The question is "what is the equation of the tangent line of x^2+xy+y^2=7 parallel to the x-axis?"2012-09-28
  • 0
    The tangent line occurs when $\dfrac{dy}{dx}(x)=0$. As Will pointed out you have everything needed to find it.2012-09-28

1 Answers 1