
Functions of several variables is usually found in things with physical quantities
 Particularly, physical quantities that vary in space and time (temperature in a room, pressure density in the ocean, etc. )

Often with these functions of several variables, one may need to calculate things like rate of change, approximation, minimums, maximums, and other traditional calculus operations.
Functions of 1 Variable
 Y =f(x)
 r(t) = (f(t), g(t))
 r(t) = (x, y(x))
One input, and one outputâ€¦
Functions of 2 Variables
 Known as â€śsurface equationsâ€ť