Crossword puzzle clue "x or y in an equation"

Mathematician who proved the impossibility of solving the quintic equation

Equation math

Type of math equation

Creature whose probable existence in the universe is explored by the Drake equation

Girolamo ___, Italian mathematician who first published the solution to the general cubic equation

Like the equation ax^3 + bx^2 + cx + d = 0

Magnetic equation formulated by physicist Marie

Sort of gear — sort of equation