Quadratic Factorization 5D5E20
1. The problem is to rewrite the quadratic equation $x^2 - x - r^2 = 0$ in the form $(x - a)(x + b) = 0$.
2. The general form of a quadratic equation is $x^2 + bx + c = 0$. When factored as $(x - a)(x + b) = 0$, it expands to $x^2 + (b - a)x - ab = 0$.
3. Comparing coefficients from $x^2 - x - r^2 = 0$ and $x^2 + (b - a)x - ab = 0$, we get:
- Coefficient of $x$: $b - a = -1$
- Constant term: $-ab = -r^2$ which implies $ab = r^2$
4. We need to find $a$ and $b$ such that:
$$b - a = -1$$
$$ab = r^2$$
5. From $b = a - 1$, substitute into $ab = r^2$:
$$a(a - 1) = r^2$$
$$a^2 - a - r^2 = 0$$
6. Solve this quadratic for $a$ using the quadratic formula:
$$a = \frac{1 \pm \sqrt{1 + 4r^2}}{2}$$
7. Then $b = a - 1$.
8. Therefore, the factorization is:
$$(x - a)(x + b) = 0$$
where
$$a = \frac{1 + \sqrt{1 + 4r^2}}{2} \text{ or } \frac{1 - \sqrt{1 + 4r^2}}{2}$$
and
$$b = a - 1$$
This completes the factorization of the quadratic equation.