The late Tokugawa shogunate or last shogun (幕末; Bakumatsu) is the period between 1853 and 1867 during which Japan ended its isolationist foreign policy and modernized from a feudal shogunate to the Meiji government. It is at end of Edo period and preceeded by Meiji era.
... other. (In this case, the parabola does not intersect the x-axis at all.)
Note that when computing roots numerically, the usual form of the quadratic formula is not ...