Let ` vec a , vec b ,a n d vec c` be vectors forming right-hand traid. Let ` vec p=( vec bxx vec c)/([ vec a vec b vec c]), vec q=( vec cxx vec a)/([ vec a vec b vec c]),a n d vec r=( vec axx vec b)/([ vec a vec b vec c]),dot` If `x in R^+,` then
a. `x[ vec a vec b vec c]+([ vec p vec q vec r])/x` has least value `=2`. b. `x^4[ vec a vec b vec c]^2+([ vec p vec q vec r])/(x^2)` has least value `=(3/2)^(2//3)` c. `[ vec p vec q vec r]>0` d. none of these