sand dollar. n. 1. Any of various thin circular echinoderms of the order Clypeasteroida, especially Echinarachnius parma, of coastal northern Atlantic and Pacific waters, having a covering of short movable spines.
One reason why linear algebra is very useful is that linear transforms of normal variables are normal. If x ~ N(a, A), then Bx+b ~ N(Ba+b, BABT). In a way, when everything is linear and normal, everything is nice and analytically tractable.
Linear equations can take several forms, such as the point-slope formula, the slope-intercept formula, and the standard form of a linear equation. These forms allow mathematicians to describe the exact same line in different ways.This can be confusing, but itâs actually quite useful.inear equations can take several forms, such as the point-slope formula, the slope-intercept formula, and the standard form of a linear equation. These forms allow mathematicians to describe the exact same line in different ways. This can be confusing, but itâs actually quite useful.