Graph the equation given by x^2 + 4y^2 = 8 and plot the coordinate (2,-1) . Find the slope of the line tangent to the curve at this point.

Compute the slope of the line tangent to the curve y^3 + y^2 5y x^2 = 4 at the point (1, 3).

Compute the slope of the line tangent to the curve x*y = 4 at the point (4, 1).

Compute the slope of the line tangent to the curve x^3 + y^3 6xy = 0 at the point( 3,3 ).