For zeros of the function (y is the function, a function of x) we need y = 0 so that in turn means we need - 9x - 1 = 0 or - 9x = 1 (i.e. add 1 to both sides); now divide by - 9, and x = 1/-9 which is exactly the same as - 1/9 or - (1/9) and this is the only zero of the function.
