Hi, just checking with 13b, can we say it's not well-defined because cross products are only defined in three dimensional space (R3) as the answer becomes -7 x ?

[K]13 Let u = (1, 2, 3), v = (1,0), y = (-1, 0, -2), z = (0, 2, 1). For each of the expressions below either explain why the given quantity is not well- defined, or if it is well-defined, evaluate it and give a geometrical interpretation of your answer. a. u - y) . V; b. (u . y Xz; c. u . (y X z)