[tex]1) \\ \\ \frac{1}{2} - \frac{1}{3} - \frac{1}{4} = \frac{1 \times 6}{2 \times 6} - \frac{1 \times 4}{3 \times 4} - \frac{1 \times 3}{4 \times 3} = \frac{6}{12} - \frac{4}{12} - \frac{3}{12} = \frac{6 - 4 - 3}{12} = - \frac{1}{12} \\ \\ 2 \sqrt{12} - 5 \sqrt{3} + \sqrt{48} = 2 \times 2 \sqrt{3} - 5 \sqrt{3} + 4 \sqrt{3} = 4 \sqrt{3} - 5 \sqrt{3} + 4 \sqrt{3} = 3 \sqrt{3} \\ \\ {5x}^{2} + {3}^{2} - {9x}^{2} = {5x}^{2} + 9 - {9x}^{2} = ( {5x}^{2} - {9x}^{2}) + 9 = - {4x}^{2} + 9 \\ \\ 2) \\ \\ x - \frac{7}{3} = - \frac{1}{3} \\ \\ x = - \frac{1}{3} + \frac{7}{3} = 2 \\ \\ {x}^{2} + 4x + 4 = \\ \\ {x}^{2} + 2x + 2x + 4 = \\ \\ x \times (x + 2) = \\ \\ 2 \times (x + 2) = \\ \\ (x + 2) \times (x + 2) = \\ \\ {(x + 2)}^{(1 + 1)} = \\ \\ (x + 2) ^{2} [/tex]
