Răspuns:
[tex]( \frac{1}{2x + 1} + \frac{1}{2x - 1} ) \times (x - \frac{1}{4x} ) = \frac{2x - 1 + 2x + 1}{(2x + 1) \times (2x - 1)} \times \frac{4x {}^ {2 } - 1 }{4x} = \frac{4x}{(2x + 1) \times (2x - 1)} \times \frac{(2 \times - 1) \times (2x + 1)}{4 \times } = 1[/tex]
[tex]( \frac{1}{3x - 2} - \frac{1}{3x + 2} ) \div ( 1 + \frac{4}{9x {}^{2} - 4} ) = \frac{3x + 2 - (3x - 2)}{(3 \times - 2) \times (3x + 2)} + \div \frac{9 {x}^{2} }{9x {}^{2} - 4 } = \frac{3 \times + 2 - 3 \times + 2}{(3 \times - 2) \times (3x + 2)} \times \frac{9 {x}^{2} - 4 }{9 {x}^{2} } = \frac{4}{(3x - 2) \times (3 x + 2) } \times \frac{(3 \times - 2) \times (3 x + 2)}{9 {x}^{2} } = 4 \frac{1}{9 {x}^{2} } = \frac{4}{9 {x}^{2} } [/tex]
