How can I draw together the function f(x,y)=(x.y^2)+1 and its tangent plane at the point (2,1,f(1,2)) in each of the following rectangles? 

(Note that the equation of the tangent plane at the given point is z=x+4y-3)

a. 2<=x<=3 and 1<=y<=3

b. 2<=x<=2.1 and 1<=y<=1.2

c. 2<=x<=2.01 and 1<=y<=1.02

How do I plot a piece of the implicit curve y^4=y^2-x^2 (when x = 0.1 .. 0.3 and y = 0.1 .. 0.3) and the point (0.2, 0.2043096437) on the curve with a different color compared to the implicit curve? I want that both x axis and y axis represents the interval (-0.5,0.5).

I'm using Maple 18

I have written the following commands in Maple 18.

implicit_func := x^3+y^3 = 9*x*y;
c := 2;
s := evalf(solve(subs(x = c, implicit_func)));
m1 := evalf(eval(implicitdiff(implicit_func, y, x), {x = c, y = s[1]}));
                          0.8000000000
m2 := evalf(eval(implicitdiff(implicit_func, y, x), {x = c, y = s[2]}));
                          -1.257321410
m3 := evalf(eval(implicitdiff(implicit_func, y, x), {x = c, y = s[3]}));
                          0.4573214099

How can I graph all "implicit_func, y - s[1] = m1*(x-c), y - s[2] = m2*(x-c), y - s[3] = m3*(x-c), and the points (c,s[1]), (c,s[2]), and (c,s[3])" in a plane? (Each of them in a different color)     

I am writting the following commands in Maple 18.

imp_fun := -4*x + 10*(x^2)*(y^(-2)) + y^2 =11: c := 2: s := evalf( solve( subs( x = c, imp_fun))): m1 := evalf( subs ( { x = c, y = s[1] }, implicitdiff( imp_fun, y,x)));

Now I expect to see a value for m1 but I see again the last command in blue.

Could you please help me to see the value for m1 by writting these commands?