1. **State the problem:** We want to analyze the function $y = -x^3 + 6x^2$ and understand its graph using the slope of the tangent line.
2. **Formula for slope of tangent line:** The slope of the tangent line at any point $x$ on the curve is given by the derivative $y' = \frac{dy}{dx}$.
3. **Find the derivative:**
$$y = -x^3 + 6x^2$$
Using power rule:
$$y' = -3x^2 + 12x$$
4. **Interpretation:** The slope $y' = -3x^2 + 12x$ tells us how steep the curve is at any $x$.
5. **Find critical points (where slope = 0):**
$$-3x^2 + 12x = 0$$
Factor out $-3x$:
$$-3x(x - 4) = 0$$
So,
$$x = 0 \quad \text{or} \quad x = 4$$
6. **Determine nature of critical points:**
Second derivative:
$$y'' = \frac{d}{dx}(-3x^2 + 12x) = -6x + 12$$
Evaluate at $x=0$:
$$y''(0) = 12 > 0$$ (local minimum)
Evaluate at $x=4$:
$$y''(4) = -6(4) + 12 = -24 + 12 = -12 < 0$$ (local maximum)
7. **Find function values at critical points:**
$$y(0) = 0$$
$$y(4) = -(4)^3 + 6(4)^2 = -64 + 96 = 32$$
8. **Summary:**
- The graph has a local minimum at $(0,0)$.
- The graph has a local maximum at $(4,32)$.
- The slope of the tangent line changes sign at these points, indicating peaks and valleys.
This analysis helps sketch the graph and understand its shape using tangent slopes.
Tangent Slope Aedf75
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