Question

a(-3; 4; 0)
b(4; 0; 3)
c(0; -3; -4)
(a+2b-c) (a+2b-c)=?

Answer 1

$a(-3,4,0); ;; b(4,0,3); ;; c(0,-3,-4)\\a+2b-c=(-3+8-0;, 4+0+3;, 0+6+4)=(5;7;10)\\(a+2b-c)^2=25+49+100=174\\P.S.; ; a^2=|a|^2=x^2+y^2+z^2$