\( \left. \begin{array} { l } { x = 7 ^ { a } + 2 } \\ { y = 7 ^ { - a } - 2 } \end{array} \right\} \Rightarrow y = ? \)

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

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

Rewrite the following without an exponent \[ (-7)^{-2} \]

Simplify. \( [32-(15+5) \div 4]-[56 \div(8-1)]^{\prime} \) \( [32-(15+5) \div 4]-[56 \div(8-1)]=\square \)

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