Question

Resolva o sistema linear

x+3y-z=2
2x+4y+z=7
3x+9y-3z=8

Answer 1

$x+3y-z=2 \\ 2x+4y+z=7 \\ 3x+9y-3z=8 \\ \left[\begin{array}{ccc}1&3&-1\\2&4&1\\3&9&-3\end{array}\right]. \left[\begin{array}{ccc}x\\y\\z\end{array}\right] = \left[\begin{array}{ccc}2\\7\\8\end{array}\right] \\ detA= \left[\begin{array}{ccc}1&3&-1\\2&4&1\\3&9&-3\end{array}\right] =-12+9-18+12-9+18=0 \\ detx= \left[\begin{array}{ccc}2&3&-1\\7&4&1\\8&9&-3\end{array}\right]=-24+24-72+32-18+72=+14 \\ x= \frac{14}{0} que impossivel \\ se detA=0 \\ logo o sistema é impossivel$