1. **State the problem:** We need to sketch the function $$y = (x-1)(x^2 + x + 1)$$.
2. **Recall the formula and rules:** This is a product of a linear term and a quadratic term. To understand the graph, we find intercepts, critical points, and behavior.
3. **Find the x-intercepts:** Set $$y=0$$:
$$0 = (x-1)(x^2 + x + 1)$$
This implies either $$x-1=0$$ or $$x^2 + x + 1=0$$.
4. Solve $$x-1=0$$:
$$x=1$$.
5. Solve $$x^2 + x + 1=0$$:
Calculate discriminant $$\Delta = b^2 - 4ac = 1^2 - 4\cdot1\cdot1 = 1 - 4 = -3 < 0$$.
Since $$\Delta < 0$$, no real roots here.
6. **Therefore, the only x-intercept is at $$x=1$$.**
7. **Find the y-intercept:** Set $$x=0$$:
$$y = (0-1)(0^2 + 0 + 1) = (-1)(1) = -1$$.
8. **Find critical points:** Differentiate using product rule:
$$y = (x-1)(x^2 + x + 1)$$
$$y' = (x-1)'(x^2 + x + 1) + (x-1)(x^2 + x + 1)'$$
$$= 1 \cdot (x^2 + x + 1) + (x-1)(2x + 1)$$
9. Simplify:
$$y' = x^2 + x + 1 + (x-1)(2x + 1)$$
$$= x^2 + x + 1 + (2x^2 + x - 2x -1)$$
$$= x^2 + x + 1 + 2x^2 - x - 1$$
$$= (x^2 + 2x^2) + (x - x) + (1 - 1) = 3x^2$$
10. Set $$y' = 0$$:
$$3x^2 = 0 \implies x=0$$.
11. **Evaluate $$y$$ at $$x=0$$:**
$$y(0) = (0-1)(0^2 + 0 + 1) = -1$$.
12. **Summary:**
- x-intercept at $$x=1$$
- y-intercept at $$y=-1$$
- Critical point at $$(0,-1)$$
- Since $$y' = 3x^2 \geq 0$$ for all $$x$$, the function is increasing except at $$x=0$$ where slope is zero.
13. **Sketch notes:** The graph touches the x-axis at $$x=1$$ and has a minimum or flat point at $$(0,-1)$$.
Final answer: The function $$y = (x-1)(x^2 + x + 1)$$ has one real root at $$x=1$$, a y-intercept at $$-1$$, and a critical point at $$(0,-1)$$ where the slope is zero. The derivative shows the function is increasing everywhere else.
Sketch Product 493D46
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