In the coefficient of x is 3, the coefficient of y is 2 and 1 is just a constant.
For non linear powers such as then the coefficient of is 3, the coefficient of is -2 and 1, although a constant can be thought of as the coefficient of
Coefficients don't have to be just numbers though, they can be constants. For example: (where k is a positive constant)
Coefficients are used mainly for working out cubics by inspection and using the factor/remainder theorem. In chemistry they are widely used to balance equations