Question 932858
There is a general quartic formula (see https://en.wikipedia.org/wiki/Quartic_function#General_formula_for_roots), but memorizing it is not practical, and usually the best way to solve it is by computer.


Some quartics can be solved easily without computer, for example x^4 + 4x^3 + 6x^2 + 4x + 1 = 16 since the LHS factors to (x+1)^4, so x+1 = 2, -2, 2i, or -2i. But most can't be solved that easily.