Question

Trong Ví dụ 3, tính \(\left(\overrightarrow{a}+\overrightarrow{b}\right)^2\).

Answer 1

\(\overrightarrow{a}+\overrightarrow{b}=\left(1-4;4+1;2+0\right)\)

=>\(\overrightarrow{a}+\overrightarrow{b}=\left(-3;5;2\right)\)

=>\(\left(\overrightarrow{a}+\overrightarrow{b}\right)^2=\left(-3\right)\cdot\left(-3\right)+5\cdot5+2\cdot2=9+25+4=38\)