12. Sjmplify \( 36 a^{2} b^{3} \div 24 a^{3} b^{-2} \).

4.2.4 Use your graph to determine the values of \( x \) for which \( \frac{4}{x-1} \geq-2 \)

Solve for \( x \) and \( y \) simultaneously: \( 3^{x+y}=27 \quad \) and \( \quad x^{2}+y^{2}=17 \)

5. In un rettangolo un lato misura 1 unità più dell'altro. Detta \( x \) la misura del lato minore, esprimi, in funzione di \( \left[A(x)=x^{2}+x+\frac{1}{4}\right] \)

\( 6 x^{3}-5 x^{7}+6 \) leading term? Leading cafficient? Turning Caint?

7. Show that the set F of the six complex valued functions: \( f_{1}(z)=z, f_{2}(z)=\frac{1}{1-z}, f_{3}(z)=\frac{z-1}{z} \) \( f_{4}(z)=\frac{1}{z}, f_{5}(z)=1-z, f_{6}(z)=\frac{z}{z-1} \) is a group under the usual multiplication of mappings.