To do this, we set $f(x) = 0$ and solve for x:
$50 - 2x^2 = 0$
$2x^2 = 50$
$x^2 = 25$
$x = \pm 5$
Since we are only considering the interval [0, 8], we only care about the positive root, $x = 5$. This means the function crosses the x-axis at $x = 5$.
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