Rút gọn các phân thức sau:
a) \(\frac}\);
b) \(\frac{{{{\left( {2x + 3} \right)}^2} + 2\left( {4{x^2} - 9} \right) + {{\left( {2x - 3} \right)}^2}}}{{{{\left( {2x - 3} \right)}^2} - 2\left( {4{x^2} - 9} \right) + {{\left( {2x + 3} \right)}^2}}}\);
c) \(\frac{{{{\left( {2x + 3} \right)}^3} - {{\left( {2x - 3} \right)}^3}}}{{{{\left( {3x + 4} \right)}^2} + 3{x^2} - 24x - 7}}\);
d) \(\frac{{\left( {x + 1} \right)\left( {x + 2} \right)\left( {x + 3} \right)\left( {x + 4} \right) + 1}}{{{x^2} + 5x + 5}}\);
e) \(\frac{{{x^4} + 4}}{{x\left( {{x^2} + 2} \right) - 2{x^2} - {{\left( {x - 2} \right)}^2} - 1}}\).
