1. **State the problem:** We are given the quadratic function $y = -x^2 - 2x + 3$ and want to analyze it.
2. **Formula and rules:** The general form of a quadratic function is $y = ax^2 + bx + c$.
- Here, $a = -1$, $b = -2$, and $c = 3$.
- Since $a < 0$, the parabola opens downward.
3. **Find the vertex:** The vertex $x$-coordinate is given by $x = -\frac{b}{2a}$.
$$x = -\frac{-2}{2 \times -1} = -\frac{-2}{-2} = -1$$
Substitute $x = -1$ into the function to find $y$:
$$y = -(-1)^2 - 2(-1) + 3 = -1 + 2 + 3 = 4$$
So the vertex is at $(-1, 4)$.
4. **Find the $y$-intercept:** Set $x=0$:
$$y = -0^2 - 2(0) + 3 = 3$$
So the $y$-intercept is $(0, 3)$.
5. **Find the $x$-intercepts:** Set $y=0$ and solve for $x$:
$$0 = -x^2 - 2x + 3$$
Multiply both sides by $-1$ to simplify:
$$0 = x^2 + 2x - 3$$
Factor the quadratic:
$$0 = (x + 3)(x - 1)$$
So the solutions are $x = -3$ and $x = 1$.
6. **Summary:**
- Vertex: $(-1, 4)$
- $y$-intercept: $(0, 3)$
- $x$-intercepts: $(-3, 0)$ and $(1, 0)$
- Parabola opens downward because $a = -1 < 0$.
Final answer: The vertex is at $(-1, 4)$, the parabola opens downward, and the intercepts are $(0, 3)$, $(-3, 0)$, and $(1, 0)$.
Quadratic Analysis 61B736
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