Question

Câu 8 nha mn :)) 

Answer 1

Lời giải:

\(\overrightarrow{i}+\overrightarrow{j}=m\overrightarrow{a}+n\overrightarrow{b}\)

\(\Leftrightarrow (1,0)+(0,1)=(-m,2m)+(3n,-5n)\)

\(\Rightarrow \left\{\begin{matrix} 1+0=-m+3n\\ 0+1=2m-5n\end{matrix}\right.\Leftrightarrow \left\{\begin{matrix} -m+3n=1\\ 2m-5n=1\end{matrix}\right.\Leftrightarrow\left\{\begin{matrix} m=8\\ n=3\end{matrix}\right.\)

Đáp án B