1. The problem asks for the basic formula, but it is not specified which formula is needed. 2. In algebra, a common basic formula is the quadratic formula used to solve equations of the form $ax^2 + bx + c = 0$. 3. The quadratic formula is: $$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$ 4. This formula gives the solutions (roots) of the quadratic equation. 5. Important rules: - $a \neq 0$ because then it wouldn't be quadratic. - The discriminant $\Delta = b^2 - 4ac$ determines the nature of the roots. - If $\Delta > 0$, two real roots. - If $\Delta = 0$, one real root. - If $\Delta < 0$, two complex roots. 6. This formula is fundamental in algebra for solving quadratic equations.