Check if coordinates are a solution to simple systems in javascript

coordinates-system-solution-checker.js

// Coordinates to check system against
const coordinates = [
    [-3, 0],
    [5, 1],
    [-4, 3],
    [2, -6],
];

// System without solving for Y
function system1(x, y) {
    return (3 * x) + (2 * y) === -6;
}

// System solved for Y.
function system2(x, y) {
    return y == (-3 * x) - 9;
}

function systemTest(x, y) {
    return [
        [x, y], // Print coordinate pair currently testing
        system1(x, y) && system2(x, y) // Check coordinate pair
    ];
}

document.write(JSON.stringify(
    coordinates.map(value => systemTest(...value)) // Test each coordinate
));