2. Expand and simplify \( \begin{array}{ll}\text { a. } 2(x+3) & \text { b. } \quad x\left(x^{2}-3 x\right) \\ \text { c. } \quad(x+7)(x-5) & \text { d. } \quad(x-3)^{2}\end{array} \)

a) \( x+y=2 \) b) \( x+x-y=4+y \)

\( \begin{array}{l}\text { Simplify the expression. Assume that variables represent } \\ \text { non-zero real numbers. }\end{array} \) \( \begin{array}{ll}\frac{6 a^{5}\left(a^{-2}\right)^{6}}{\left(a^{-1}\right)^{-3}} & \frac{6 a^{5}\left(a^{-2}\right)^{6}}{\left(a^{-1}\right)^{-3}}=\square \\ \text { (Simplify your answer. Type in exponenti. } \\ \text { notation. Type positive exponents.) }\end{array} \)

Calcule todos los valores de a para los cuales la matriz \( A=\left[\begin{array}{lll}a & 0 & 4 \\ 1 & 1 & a \\ a & 1 & 2\end{array}\right] \) es no invertit

Résoudre dans \( \mathbb{C}: \mathrm{z}^{7}=1 \)

\( 1 \leftarrow \) Show that \( A I=I A=A \). \( A=\left[\begin{array}{rr}1 & 8 \\ -2 & 2\end{array}\right] \)