I'm a bit confused about this implicit differentiation question.
Find the equation of the tangent to the curve 2x2 + y - xy2 - 2y3 = 4 at the point (-1, -1).
I am confused because substituting the x and y coordinates into the above equation does not equal to 4. Does this simply mean that the line is not on the curve?
I solved for dy/dx and got (-4x - y2) / (1-x2y-6y3) and substituting (-1, -1) into this equation I got the slope of the tangent to the curve to be y= 1/3 (x+1) -1.
Does this seem right?