1. The problem is to analyze the function $y=2x^3 - x^2$.
2. First, identify the function type: it is a cubic polynomial.
3. To find intercepts:
- **y-intercept**: Set $x=0$, then $y=2(0)^3 - (0)^2=0$.
- **x-intercepts**: Set $y=0$, solve $2x^3 - x^2=0$.
4. Factor the equation:
$$x^2(2x - 1) = 0$$
5. Set each factor equal to zero:
- $x^2=0 \Rightarrow x=0$
- $2x - 1=0 \Rightarrow x=\frac{1}{2}$
6. So, the x-intercepts are at $x=0$ and $x=\frac{1}{2}$.
7. To find extrema, compute the derivative:
$$y' = \frac{d}{dx}(2x^3 - x^2) = 6x^2 - 2x$$
8. Set derivative equal to zero to find critical points:
$$6x^2 - 2x = 0$$
9. Factor:
$$2x(3x - 1) = 0$$
10. Solve for $x$:
- $2x=0 \Rightarrow x=0$
- $3x - 1=0 \Rightarrow x=\frac{1}{3}$
11. Evaluate $y$ at critical points:
- At $x=0$: $y=0$
- At $x=\frac{1}{3}$: $y=2\left(\frac{1}{3}\right)^3 - \left(\frac{1}{3}\right)^2 = 2\cdot\frac{1}{27} - \frac{1}{9} = \frac{2}{27} - \frac{3}{27} = -\frac{1}{27}$
12. Determine the nature of critical points using the second derivative:
$$y'' = \frac{d}{dx}(6x^2 - 2x) = 12x - 2$$
13. Evaluate $y''$ at critical points:
- At $x=0$: $y'' = 12(0) - 2 = -2 < 0$, so local maximum.
- At $x=\frac{1}{3}$: $y'' = 12\cdot\frac{1}{3} - 2 = 4 - 2 = 2 > 0$, so local minimum.
**Final answer:**
- x-intercepts at $x=0$ and $x=\frac{1}{2}$
- y-intercept at $(0,0)$
- Local maximum at $(0,0)$
- Local minimum at $\left(\frac{1}{3}, -\frac{1}{27}\right)$
Cubic Analysis
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.