# What is the slope of the tangent line of  (3x)/y-(4x^2)/(1-y)^2 =C , where C is an arbitrary constant, at (1,2)?

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$\frac{x \left(8 x {y}^{2} - 3 {y}^{3} + 9 {y}^{2} - 9 y + 3\right)}{y \left(8 x {y}^{2} - 3 {y}^{3} - 8 x y + 9 {y}^{2} - 9 y + 3\right)} = 0$