How do people come up with equations and know so little about them? When you invent an equation, you know best about the equation you discovered, correcto? Like Navier-Strokes equation, those guys discovered it, and now the equation is considered "unsolved", how so?? Where's those guys? Why don't they solve their own equations? They discovered it! How do they discover it and still know "little" about it, and it's still "unsolved" ?

Example, if I came up with a+b=c, then I know how to use the equation in everyday, which in this case, to substitute. 1+1=2

Please explain to mo, I'm confused

Example, if I came up with a+b=c, then I know how to use the equation in everyday, which in this case, to substitute. 1+1=2
a = b?

a+b=c
1+2+3

The Navier-Stokes equation covers velocity as well as position of fluids. Since studying velocity instead of position makes more sense for a fluid, mathematicians are puzzled as to how to use the equation at times. Wikipedia has a long article about it.