Trong gian Oxyz, cho ba véc tơ a(5;7;2), b(3;0;4)

Câu hỏi :

Trong không gian Oxyz, cho ba véc tơ $\stackrel{\rightharpoonup }{a}(5;7;2), \stackrel{\rightharpoonup }{b}(3;0;4), \stackrel{\rightharpoonup }{c}(-6;1;-1)$  Hãy tìm véc tơ $\stackrel{\rightharpoonup }{n}=3\stackrel{\rightharpoonup }{a}-2\stackrel{\rightharpoonup }{b}+\stackrel{\rightharpoonup }{c}$ .