 Hi and welcome to the session. Let us understand the following question today. Through the following, 3 cos inverse x is equal to cos inverse of 4x cube minus 3x, where x belongs to closed interval half comma 1. Now, before writing the solution, let us write the identity that we will be using in the question. Which says cos 3 theta is equal to 4 cos cube theta minus 3 cos theta, which is the key idea to our question. Now, let's proceed with our solution. Let us suppose that cos inverse of x is equal to theta, which implies x is equal to cos theta. Now, using our identity, cos 3 theta is equal to 4x cube minus 3x, or 3 theta is equal to cos inverse of 4x cube minus 3x. Here we have assumed theta is equal to cos inverse x, so substituting theta is equal to cos inverse x, we get 3 cos inverse x is equal to cos inverse of 4x cube minus 3x. And this is our required result. I hope you understood the session. Bye and have a nice day.