Floating point accuracy

I am writing a method which calculates the equation of a 2D Line in the form a*x+b*y=1

//Given two points, find the equation of the line by solving two linear equations and then test the result. (For simplicity, assume that delta !=0 here)

private boolean solveAndRetry(float x1,float y1, float x2,float y2) {
        float delta = x1 * y2 - x2 * y1;
        float deltaA = y2 - y1;
        float deltaB = x1 - x2;

        float a = deltaA / delta;
        float b = deltaB / delta;
        float c = 1;

        //test
        if (a * x2 + b * y2 == c) {
        System.out.println("ok");
            return true;
        }
        else {
            System.out.println(a * x2 + b * y2-c);
            return false;
        }
    }

When I ran it, I was expecting there would be all "ok"s, but that's not the case and I don't know why

public static void main(String[] args) {
        for (float x = 0; x < 10; x += 0.01f) {
            solveAndRetry(1, -1, x, 2);
        }
    }

Here are some lines in the result

ok
ok
ok
ok
ok
ok
ok
ok
-5.9604645E-8
ok
-5.9604645E-8
ok
ok
ok
1.1920929E-7
ok
ok
-5.9604645E-8
ok