MATLAB: Plotting a bivariate function and a tangent line on the same graph

3d plotsequationfunctionfunctionsmatrixnonlineartangenttangent line

I'm currently attempting to plot two functions, f(x,y) = x^2 + 3(x^2)y + 3 and 14(x-1) + 3(y-2) = 0, onto the same graph, however I'm finding extreme trouble (likely because of my inexperience) plotting the two simultaneously. The only part I understand thus far is that f(x,y) can't be converted to matrix form (required to plot in 3D) as it's not a linear function.
If someone is willing and able to walk me through the process of doing this, that would be greatly appreciated.

Best Answer

To plot them simultaneously, you need to use the hold function.
See if this does what you want: 
f = @(x,y) x.^2 + 3*(x.^2).*y + 3;                                  % Anonymous Function

g = @(x,y) 14*(x-1) + 3*(y-2);                                      % Anonymous Function
[X,Y] = ndgrid(linspace(-10,10, 250));                              % Define Matrix Arguments
figure
mesh(X, Y, f(X,Y))                                                  % Plot Surface
hold on
contour3(X, Y, g(X,Y), [0 0], 'Color','r', 'LineWidth',2)           % Plot Implicit Function
hold off
grid on
view(30,30)
Experiment to get the result you want.
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