Plot the following density plots?

Questions
1

Hi I have a problem that I think that is simple, but I don’t know how to write it in code.

Suppose that you have a function f(x)=l_{0}x^{2} and you want to plot it as a function of x In the interval x\in[0,10]. I Know that i can do it as

Plot[Evaluate[f(x)], {x,  0 , 10, PlotRange -> All]

But the problem is that i have another function that depends of l_{0}, and I want to plot in the same graph, but the x-axis can’t be used anymore. However, I have seen in some papers link that they use some kind of density plot, but i don’t know how to do it, can you help me?

2

I think that the correct name of this kind of plots is “Plot of Parameter space”.