Testing elliptic curve addition formulas

function test_the_formula(A, B, x1, x2)
{
    const E = x => Math.sqrt(x**3 + A*x + B);

    const y1 = E(x1);
    const y2 = E(x2);
    const m = (y2 - y1)/(x2-x1);

    const x3_a = m**2 - x1 - x2;
    const x3_b = (m**2*x1 + x1**2 + A - 2*m*y1)/x2;

    return Math.abs(x3_a - x3_b) < 0.00000001;
}

function test()
{
    for (let A = 1; A < 100; A++)
        for (let B = 1; B < 100; B++)
        {
            let x1 = Math.floor(Math.random()*10) + 1;
            let x2 = x1;

            while (x1 == x2)
                x2 = Math.floor(Math.random()*10) + 1;

            if ( ! test_the_formula(A, B, x1, x2))
            {
                console.log(`A = ${A}; B = ${B}; x1 = ${x1}; x2 = ${x2}`);
                return false;
            }
        }

    return true;
}