Did You Get This One?

Can you get this one? I had a hard time even after I was given an important clue. One of these equations did not transform into the intended image in my mind and that threw me off, because I worked on that equation first. I saw it as a different image. When I left it and worked on the two other equations, I realized the first answer and finally got this brain meme.

Brain Meme_hard1

If you did not get the clue in the post, I will give it later in the comments section.