Quadratic Solve 9A09Ef
1. **State the problem:** Solve the quadratic equation $$x^2 - 25 = 0$$ and sketch its graph.
2. **Formula and rules:** The standard form of a quadratic equation is $$ax^2 + bx + c = 0$$.
To solve, use factoring, completing the square, or the quadratic formula:
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
3. **Apply to the equation:** Here, $$a=1$$, $$b=0$$, $$c=-25$$.
4. **Solve by factoring:**
$$x^2 - 25 = (x - 5)(x + 5) = 0$$
5. **Find roots:**
Set each factor to zero:
$$x - 5 = 0 \Rightarrow x = 5$$
$$x + 5 = 0 \Rightarrow x = -5$$
6. **Graph explanation:**
The parabola opens upward (since $$a=1 > 0$$).
The vertex is at $$x=0$$, $$y = -25$$.
The roots (x-intercepts) are at $$x = -5$$ and $$x = 5$$.
7. **Final answer:**
The solutions are $$x = -5$$ and $$x = 5$$.
The graph is a parabola opening upward with vertex at $$(0, -25)$$ and x-intercepts at $$(\pm 5, 0)$$.