Hi Alicia,

A rational function is one that can be written as the quotient of two polynomials so an irrational function is one that cannot be written as the quotient of two polynomials. When I think of irrational functions I first think of three large classes, functions that involve radicals, the trigonometric functions and the logarithmic/exponential functions.

There are some "outside school" places where functions that involve radicals and logarithmic functions in the answer we gave to an earlier question. Trigonometric functions abound in many applications. Go to the Quandaries and Queries page on Math Central and type trig real life into the Quick Search window to see some examples.

Harley