=2*a¯^2+a*b-6b¯^2
a^2=|a¯|*|a¯|*cos 0=|a¯|^2
|a¯|=sqrt(4^2+(-2)^2+(-4)^2)=sqrt(36)=6
b^2=|b¯|*b¯|*cos 0=|b¯|^2
|b¯|=sqrt(6^2+(-3)^2+2^2)=sqrt(49)=7
a*b=4*6+(-2)*(-3)+(-4)*2=24+6-8=22
О т в е т. (2a¯−3b¯)(a¯+2b¯) =
=2*a¯^2+a*b-6b¯^2=
=2*6^2+22-6*7^2=-200