We can do this by evaluating the function at the endpoints of the interval. If the function changes sign, then by the Intermediate Value Theorem, there must be a root in the interval.
We have $f(0) = (0)^4 - (0)^2 + 3(0) - 1 = -1$ and $f(1) = (1)^4 - (1)^2 + 3(1)
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