Kelly's story is truly inspirational. Kelly has shown that pure determination, dedication and hard work can and does change a person's life. At Life Leisure we have loved being part of Kelly's journey.
In calculus (a branch of mathematics), a differentiable function of one real variable is a function whose derivative exists at each point in its domain.
In mathematics, a function is a relation between a set of inputs and a set of permissible outputs with the property that each input is related to exactly one output.