Calculați:

a)

[tex]x - \frac{ {x}^{2} - 4 }{2x + 1} \times \frac{2x + 1}{x - 2} + [\frac{(x - 1)^{2} \times (5x + 3) }{4x + 7}]^{3} \times \frac{(4x + 7) ^{3} }{(x - 1)^{5}(5x + 3)^{3} } [/tex]

b)

[tex]( \frac{3}{5 + 2x} + \frac{1}{x - 1}) \times \frac{4x + 10}{5x + 2} + \frac{9 - {x}^{2} }{4x + 7}:\frac{3 + x}{4x + 7} [/tex]

c)

[tex]( \frac{1}{2 {x}^{2} - 7 } - \frac{4x}{3 {x}^{2} - 7 }) \times \frac{3 {x}^{2} - 7 }{x + 6} + \frac{4x^{2} - 49 }{ {x}^{2} - 36 }:\frac{2x + 7}{x - 6} [/tex]

d)

[tex]( \frac{2}{x - 2} - \frac{3}{x + 3}) \times \frac{5x(x + 3)}{12 - x} - \frac{8}{x - 2} + \frac{81}{ {x}^{2} - 4 } + \frac{x + 2}{9} [/tex]