Giải thích các bước giải:
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\begin{array}{l}
\overrightarrow v = 3.\overrightarrow {MA} - 5\overrightarrow {MB} + 2\overrightarrow {MC} \\
= 3.\overrightarrow {MA} - 3\overrightarrow {MB} - 2\overrightarrow {MB} + 2\overrightarrow {MC} \\
= 3.(\overrightarrow {MA} - \overrightarrow {MB} ) - 2.(\overrightarrow {MB} - \overrightarrow {MC} )\\
= 3.\overrightarrow {BA} - 2.\overrightarrow {CB} = 3.\overrightarrow {BA} + 2.\overrightarrow {BC}
\end{array}$
⇒đpcm
