The equation of a curve is $$3x^2 + 8xy + y^2 = -13.$$ Find the equations of the two tangents which are parallel to the $y$-axis.
Tangents to the curve and parallel to the $y$-axis?
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calculus
derivatives
implicit-differentiation
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0You've tagged the problem "implicit differentiation." Do you know how to do implicit differentiation? Or is that the bit you can't do? – 2012-08-09
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0Well I managed to find dy/dx in terms of x and y, but what do i do from there? dy/dx is a tangent, isn't it? – 2012-08-09
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0$dy/dx$ is the *slope* of the tangent line. You're looking for places where that slope is infinite. This will probably correspond to points where your formula for $dy/dx$ results in dividing by zero. – 2012-08-09