Finding a tangent line parallel to the x-axis with dy/dx
3
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$x^2+xy+y^2=7$
Find $dy/dx$
$dy/dx= (-2x-y)/(x+2y)$
How do I take $dy/dx$ and get the equation of the tangent line parallel to the $x$-axis?
implicit-differentiation
asked 2012-09-28
user id:42915
16
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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
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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