a) Consider the linear system \( \left\{\begin{array}{c}x-y-3 z=3 \\ 2 x+z=0 \\ 2 y+7 z=c\end{array}\right. \) i) For what value of \( c \) does the system have a solution? ii) Solve the system at the value of \( c \) from part (i)?

Calaula las saguientes determinantes \( \begin{array}{ll}\text { a) }\left|\begin{array}{cc}-8 & 9 \\ -1 & 20\end{array}\right| & \text { b }\left|\begin{array}{ll}2 & \frac{1}{3} \\ \frac{1}{2} & -1\end{array}\right| \text { c) }\left|\begin{array}{cc}5 & -a \\ 2 a & 4 a^{2}\end{array}\right|\end{array} \)

If \( 33-a=a+27-5 a \), what is the value of \( 33+3 a ? \)

\( \frac { 4 x y } { x ^ { 2 } + y ^ { 2 } } \)

Analizar y graficar 3) \( y=2 x^{2}-4 x+5 \)

Сложите почленно неравенства. \( 11<13 \) и \( 5,1>2,7 \)