Question: 4 — Graphing Quadratic Inequalities
LEARNING OBJECTIVE: Determine the graph of a quadratic inequality.
Which of the following graphs represents the quadratic inequality
y \leq 3x^2 - 6x + 1?
1. **State the problem:** We need to graph the quadratic inequality $$y \leq 3x^2 - 6x + 1$$.
2. **Understand the quadratic inequality:** The inequality involves a quadratic expression on the right side, and the inequality symbol is \(\leq\), meaning the graph includes points where $$y$$ is less than or equal to the quadratic expression.
3. **Analyze the quadratic function:** The quadratic function is $$f(x) = 3x^2 - 6x + 1$$.
- The coefficient of $$x^2$$ is positive ($$3 > 0$$), so the parabola opens upward.
4. **Graphing the parabola:**
- The parabola is solid because the inequality is \(\leq\), which includes equality.
- The vertex can be found using the formula $$x = -\frac{b}{2a}$$ where $$a=3$$ and $$b=-6$$.
Calculate the vertex x-coordinate:
$$x = -\frac{-6}{2 \times 3} = \frac{6}{6} = 1$$
Calculate the vertex y-coordinate:
$$y = 3(1)^2 - 6(1) + 1 = 3 - 6 + 1 = -2$$
So the vertex is at $$(1, -2)$$.
5. **Shading the region:**
- Since the inequality is $$y \leq 3x^2 - 6x + 1$$, the shaded region is **below** the parabola.
6. **Summary:**
- The graph is a solid parabola opening upward with vertex at $$(1, -2)$$.
- The shaded region is the area below the parabola.
This matches the description given: a solid parabola opening upward with shading below it.
**Final answer:** The graph representing $$y \leq 3x^2 - 6x + 1$$ is a solid upward-opening parabola with vertex at $$(1, -2)$$ and shading below the curve.