/ / ____ \ / ____ \\
| | 7 \/ 21 | | 7 \/ 21 ||
Or|And|x < 4, - - ------ < x|, And|x < oo, - + ------ < x||
\ \ 2 2 / \ 2 2 //
$$\left(x < 4 \wedge \frac{7}{2} - \frac{\sqrt{21}}{2} < x\right) \vee \left(x < \infty \wedge \frac{\sqrt{21}}{2} + \frac{7}{2} < x\right)$$
((x < 4)∧(7/2 - sqrt(21)/2 < x))∨((x < oo)∧(7/2 + sqrt(21)/2 < x))
____ ____
7 \/ 21 7 \/ 21
(- - ------, 4) U (- + ------, oo)
2 2 2 2
$$x\ in\ \left(\frac{7}{2} - \frac{\sqrt{21}}{2}, 4\right) \cup \left(\frac{\sqrt{21}}{2} + \frac{7}{2}, \infty\right)$$
x in Union(Interval.open(7/2 - sqrt(21)/2, 4), Interval.open(sqrt(21)/2 + 7/2, oo))