The general formula for the polynomial function is

Following this formula, you have to identify a, b and c in the given polynomial

c is the term of the function that is not related to any variable, i.e. the number that is alone, so c = -1
a is the number that is related to the variable x, in the expression that value is a = -7
b is the number that is related to the variable y, in the expression that value is b = 1/6