Identity function

Constant function

Polynomial function

The Modulus function

Rational functions

y = f(x) = x for each x ∈ R

y = f(x) = c for each x ∈ R

y = f (x) = a₀ + a₁x + a₂x² + ...+ an xⁿ, where n is a non-negative integer

f: R→R defined by f(x) = |x|

f (x) = (x²+2x+1)⁄(x²-8x+12)