website/4.8.html at main · shenyuhao1/website · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
<!DOCTYPE html>
<html>
<body>
    <input size="3" id="a" placeholder="a"> x<sup>2</sup> +
    <input size="3" id="b" placeholder="b"> x +
    <input size="3" id="c" placeholder="c"> = 0
    <input type="button" value="Solve" onclick="solve()">
    <div id="solution">Solution area</div>

    <script>
        function solve() {
            let a = document.getElementById('a');
            let b = document.getElementById('b');
            let c = document.getElementById('c'); // Correct the reference for 'c'
            let solutionArea = document.getElementById('solution');
            solutionArea.innerHTML = ""; // Clear previous solutions
            let err = '';

            if (isNaN(a.value)) {
                err = 'a is not a number.';
                a.focus();
            } else if (isNaN(b.value)) {
                err = 'b is not a number.';
                b.focus();
            } else if (isNaN(c.value)) {
                err = 'c is not a number.';
                c.focus();
            } else {
                a = parseFloat(a.value);
                b = parseFloat(b.value);
                c = parseFloat(c.value);

                if (a === 0) {
                    if (b === 0) {
                        if (c === 0) {
                            err = "Any x solves the equation.";
                        } else {
                            err = "No solution exists.";
                        }
                    } else {
                        err = "x = " + (-c / b);
                    }
                } else {
                    let delta = b ** 2 - 4 * a * c;
                    if (delta > 0) {
                        let x1 = (-b + Math.sqrt(delta)) / (2 * a);
                        let x2 = (-b - Math.sqrt(delta)) / (2 * a);
                        err = "x1 = " + x1 + ", x2 = " + x2;
                    } else if (delta === 0) {
                        let x = -b / (2 * a);
                        err = "x = " + x;
                    } else {
                        let realPart = (-b / (2 * a));
                        let imaginaryPart = Math.sqrt(-delta) / (2 * a);
                        err = "x1 = " + realPart + " + " + imaginaryPart + "i, x2 = " + realPart + " - " + imaginaryPart + "i";
                    }
                }
            }

            solutionArea.innerHTML = err; // Set computed result
        }
    </script>
</body>
</html>