1- Effectuez: $\frac{ab}{c}\cdot \frac{3c^2}{a^2}÷\frac{a^2{b}^3}{9c}$
$\frac{a{b}^4}{3}$	$\frac{27ab{c}^3}{a^4{b}^{3}c}$	$\frac{27c^2}{a^3{b}^2}$>

2- Effectuez: $\frac{42a^{3}b{c}^2}{x}÷\frac{7a{b}^{3}c}{x^3}$
$\frac{294a^4{b}^4{c}^3}{x^4}$	$\frac{42a^{3}b{c}^2{x}^3}{7a{b}^{3}cx}$	$\frac{6a^{2}c{x}^2}{b^2}$

3- Effectuez: $\frac{16x^6{y}^{2}z}{a{b}^3}\cdot \frac{7a^{2}b}{32x^{4}z}$
$\frac{7x^2{y}^{2}a}{2b^2}$	$\frac{512x^{10}{y}^2{z}^2}{7a^{3}b4}$	$\frac{112a^{2}b{x}^6{y}^{2}z}{32a{b}^3{x}^{4}z}$

4- Effectuez: $\frac{\frac{(n+1)(n+2{)}^3}{(n-1{)}^2}}{\frac{(n+1{)}^3(n+2)}{(n-1{)}^2}}$
$\frac{(n+1{)}^4(n+2{)}^2}{(n-1{)}^4}$	$\frac{(n+2{)}^2}{(n+1{)}^2}$	$\frac{(n+1)(n+2{)}^3(n-1{)}^2}{(n-1{)}^2(n+1{)}^3(n+2)}$

5- Effectuez (voir addition et soustraction): $\frac{\frac{1}{x^2}-1}{\frac{1}{x}+1}$
$\frac{1-x}{x}$	$\frac{1-x^2}{x(1+x)}$	$\frac{(1-x^2)(1+x)}{x^3}$