Accept the terms and conditions of the license by placing the switch in the appropriate position and clicking "Next".Once the package installer is on your computer, do the following: In the window that appears, uncheck the suggested additional software so that it does not load with DirectX.Go to the page of this product, after selecting the language of your system click on "Download".To download and install DirectX, older Windows owners should do the following: Read More: Reinstalling and Adding Missing DirectX Components in Windows 10 This is necessary because DirectX here is a system component and not third-party, as in previous versions of the OS. Immediately note that when using Windows 10 you must use a separate instruction. The dynamic library d3dx9_40.dll is a part of the DirectX package, so you can install this package and put it on your system.
More information: Registering a DLL file in Windows Method 2: Installing DirectX