1. **State the problem:** Complete the square for the quadratic function $y = -x^2 + 6x - 5$.
2. **Recall the formula:** To complete the square for a quadratic $ax^2 + bx + c$, factor out $a$ from the $x^2$ and $x$ terms, then add and subtract $(\frac{b}{2a})^2$ inside the parentheses.
3. **Start with the given function:**
$$y = -x^2 + 6x - 5$$
4. **Factor out the coefficient of $x^2$ from the first two terms:**
$$y = - (x^2 - 6x) - 5$$
5. **Find the value to complete the square:**
Calculate $\left(\frac{-6}{2}\right)^2 = (-3)^2 = 9$.
6. **Add and subtract 9 inside the parentheses:**
$$y = - (x^2 - 6x + 9 - 9) - 5$$
7. **Group the perfect square trinomial and simplify:**
$$y = - \big((x - 3)^2 - 9\big) - 5$$
8. **Distribute the negative sign:**
$$y = - (x - 3)^2 + 9 - 5$$
9. **Combine constants:**
$$y = - (x - 3)^2 + 4$$
**Final answer:**
$$y = - (x - 3)^2 + 4$$
This is the completed square form of the quadratic function, showing the vertex at $(3, 4)$ and that the parabola opens downward.
Complete Square 75Ed03
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.