# How to include a function plot in RegionPlot Mathematica

I have a RegionPlot graph in Mathematica, which shows the solution to complex inequalities. In the same 2-dimensional space, I would like to plot a function . Any Help?

Thanks!

#### Update 1

Here is my try which should highlight the region where t < 3/2 \[Lambda] and plot the functions. However, the command only shows the Region Plot and not the Plots

Show[RegionPlot[t < 3/2 \[Lambda], {t, 1, 2}, {\[Lambda], 17/41, 1}],
Plot[{thatLP[\[Lambda]], thatLS[\[Lambda]]}, {\[Lambda], 17/41, 1}]]


#### Update 2

Here is my try which should highlight the region where t < 3/2 \[Lambda] and plot the function t=\[Lambda]. However, the command only shows the Region Plot and not the Plots

Show[{RegionPlot[
t < 3/2  \[Lambda], {t, 1, 2}, {\[Lambda], 17/41, 1}],
Plot[t, {\[Lambda], 17/41, 1}]}]


My Regions and Functions are more complicated, but even this simple example does not work...

• Welcome to the community. I think Show could be helpful. If you add more detail about your problem, we could help you better. Dec 17, 2022 at 17:12
• Please provide a concrete example for the type of problem you are working with. Include the code (copy and paste-able InputForm) for what you have tried. Dec 17, 2022 at 17:12
• @BenIzd Thanks! I am trying with Show. For example, I am writing: Show[RegionPlot[t < 3/2 [Lambda], {t, 1, 2}, {[Lambda], 17/41, 1}], Plot[{thatLP[[Lambda]], thatLS[[Lambda]]}, {[Lambda], 0, 1}]] Which should highlight the region where t<3/2 \Lambda and Plot the functions: thatLP[[Lambda]], thatLS[[Lambda]. However, the command only shows the Region Plot and not the Plots. But if I only ask to Plot them, it works... Dec 17, 2022 at 17:40
• @BobHanlon Thanks. I am writing: Show[RegionPlot[t < 3/2 [Lambda], {t, 1, 2}, {[Lambda], 17/41, 1}], Plot[{thatLP[[Lambda]], thatLS[[Lambda]]}, {[Lambda], 0, 1}]] Which should highlight the region where t<3/2 \Lambda and Plot the functions: thatLP[[Lambda]], thatLS[[Lambda]. However, the command only shows the Region Plot and not the Plots. But if I only ask to Plot the function, it works... Dec 17, 2022 at 17:44
• If possible, please edit and add the definitions of your function (thatLP and thatLS) so that we can reproduce the output. Dec 17, 2022 at 17:51

Show[{RegionPlot[t < 3/2 \[Lambda], {t, 1, 2}, {\[Lambda], 17/41, 1}],