Question

x - 8y = 7
Is this or is this not a function?

Answer 1

For it to be a function, there must be only 1 value of y for any value of x. Another way of thinking of this is that nowhere on the graph will a vertical line cross the curve twice. Basically, if you have the equation of a line, it will be a function except for the one case of a vertical line (x = k where k is a constant)