1. Problem: Sketch the curve $y = x^3 - 6x^4 + 6$ by finding points of intersection with axes and using max/min points.
Step 1: Find x-intercepts by setting $y=0$:
$$x^3 - 6x^4 + 6 = 0$$
This is a quartic equation; approximate or factor if possible.
Step 2: Find y-intercept by setting $x=0$:
$$y = 0 - 0 + 6 = 6$$
So, y-intercept is $(0,6)$.
Step 3: Use max/min points from Progress Exercises 6.6 (assumed given).
2. Problem: Sketch the curve $y = 2x - 3x^2$.
Step 1: Find x-intercepts by setting $y=0$:
$$2x - 3x^2 = 0 \implies x(2 - 3x) = 0 \implies x=0 \text{ or } x=\frac{2}{3}$$
Step 2: Find y-intercept by setting $x=0$:
$$y=0$$
Step 3: Find max/min by differentiating:
$$y' = 2 - 6x$$
Set $y'=0$:
$$2 - 6x = 0 \implies x=\frac{1}{3}$$
Step 4: Evaluate $y$ at $x=\frac{1}{3}$:
$$y = 2\times\frac{1}{3} - 3\times\left(\frac{1}{3}\right)^2 = \frac{2}{3} - 3\times\frac{1}{9} = \frac{2}{3} - \frac{1}{3} = \frac{1}{3}$$
So, max point at $\left(\frac{1}{3}, \frac{1}{3}\right)$.
3. Problem: Sketch the curve $P = -2Q^3 + 8Q$.
Step 1: Find intercepts:
Set $P=0$:
$$-2Q^3 + 8Q = 0 \implies -2Q(Q^2 - 4) = 0 \implies Q=0, Q=\pm 2$$
Step 2: Find $P$ when $Q=0$:
$$P=0$$
Step 3: Use max/min points from Progress Exercises 6.6 (assumed given).
4. Problem: Sketch the curve $C = Y + 100$.
Step 1: This is a linear function with slope 1 and y-intercept 100.
Step 2: Intercepts:
Set $C=0$:
$$0 = Y + 100 \implies Y = -100$$
Set $Y=0$:
$$C = 100$$
Summary:
- For each curve, intercepts and max/min points are identified.
- Use these points to sketch the curves accurately.
Curve Sketching
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