Cubic Polynomial
1. We are given the function $p(u) = u^3 - 3u^2 + 4u$ with $u$ in meters. The problem involves understanding this cubic function and its interaction with the factor $(u - 2)$, which may represent a factorization or a root related to the raw material in the shoe.
2. First, factor $p(u)$ if possible. Factor out the common term $u$:
$$p(u) = u(u^2 - 3u + 4)$$
3. Next, analyze the quadratic $u^2 - 3u + 4$:
Calculate its discriminant:
$$\Delta = (-3)^2 - 4 \cdot 1 \cdot 4 = 9 - 16 = -7$$
Because $\Delta < 0$, the quadratic has no real roots, so $p(u)$ has only one real root from the factor $u = 0$.
4. The factor $(u - 2)$ given might be a proposed factor of $p(u)$ or related to raw material input. To check if $(u - 2)$ is a factor, evaluate $p(2)$:
$$p(2) = 2^3 - 3 \cdot 2^2 + 4 \cdot 2 = 8 - 12 + 8 = 4$$
Since $p(2) \ne 0$, $(u - 2)$ is not a factor.
5. To summarize the behavior:
- The curve crosses the $u$-axis at $u=0$.
- The cubic has no other real roots.
- The raw material $(u - 2)$ does not represent a root or factor for $p(u)$.
6. The local extrema can be found by taking the derivative:
$$p'(u) = 3u^2 - 6u + 4$$
Set $p'(u) = 0$:
$$3u^2 - 6u + 4 = 0$$
Calculate discriminant:
$$\Delta = (-6)^2 - 4 \cdot 3 \cdot 4 = 36 - 48 = -12$$
Since $\Delta < 0$, no critical points with real roots exist, so $p(u)$ has no local maximum or minimum. The function is strictly increasing or decreasing throughout its domain.
Final answer:
- $p(u)$ has one real root at $u=0$.
- $(u - 2)$ is not a factor.
- No local extrema exist.
- The graph’s shape confirms this behavior.