In an optimisation problem, the objective function is the function to be minimised or maximised.

For example: in the problem;

Find the maximum value for 5`x` + 2`x``y` in the area bounded by the lines `x` = -1, `x` = 1, `y` = -1, `y` = 1

the objective function is 5

`x` + 2

`x``y`.