1. The problem is to sketch the function $y = g(x) = (x + 1)(x - 2) = x^2 - x - 2$.
2. This is a quadratic function in standard form $y = ax^2 + bx + c$ where $a = 1$, $b = -1$, and $c = -2$.
3. Important properties of quadratic functions:
- The graph is a parabola.
- Since $a > 0$, the parabola opens upwards.
- The vertex can be found using the formula $x = -\frac{b}{2a}$.
- The roots (x-intercepts) are the values of $x$ where $y=0$.
4. Find the roots by factoring:
$$g(x) = (x + 1)(x - 2) = 0$$
So, $x = -1$ or $x = 2$.
5. Find the vertex:
$$x = -\frac{b}{2a} = -\frac{-1}{2 \times 1} = \frac{1}{2}$$
Substitute back to find $y$:
$$g\left(\frac{1}{2}\right) = \left(\frac{1}{2}\right)^2 - \frac{1}{2} - 2 = \frac{1}{4} - \frac{1}{2} - 2 = -\frac{9}{4}$$
6. The vertex is at $\left(\frac{1}{2}, -\frac{9}{4}\right)$.
7. The y-intercept is found by evaluating $g(0)$:
$$g(0) = (0 + 1)(0 - 2) = 1 \times (-2) = -2$$
8. Summary:
- Roots at $x = -1$ and $x = 2$
- Vertex at $\left(\frac{1}{2}, -\frac{9}{4}\right)$
- Y-intercept at $(0, -2)$
9. Sketch the parabola using these points and the fact it opens upward.
Final answer: The parabola $y = x^2 - x - 2$ has roots at $x = -1$ and $x = 2$, vertex at $\left(\frac{1}{2}, -\frac{9}{4}\right)$, and opens upward.
Quadratic Sketch 3Fc8D3
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