1. **State the problem:** We need to show that the function $f(x) = x^4 + x - 1$ has a real root $\alpha$ in the interval $[0.5, 1.0]$.
2. **Evaluate $f(x)$ at the endpoints:**
Calculate $f(0.5)$:
$$f(0.5) = (0.5)^4 + 0.5 - 1 = 0.0625 + 0.5 - 1 = -0.4375$$
Calculate $f(1.0)$:
$$f(1.0) = (1.0)^4 + 1.0 - 1 = 1 + 1 - 1 = 1$$
3. **Analyze the signs:**
At $x=0.5$, $f(0.5) = -0.4375 < 0$.
At $x=1.0$, $f(1.0) = 1 > 0$.
4. **Apply the Intermediate Value Theorem:**
Since $f(x)$ is a polynomial, it is continuous on $[0.5, 1.0]$. Because $f(0.5) < 0$ and $f(1.0) > 0$, there must be at least one $\alpha \in [0.5, 1.0]$ such that $f(\alpha) = 0$.
**Final answer:**
There exists a real root $\alpha$ of $f(x) = x^4 + x - 1$ in the interval $[0.5, 1.0]$ by the Intermediate Value Theorem.
Root Interval
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