Question

Помогите кто что сможет пожалуйста

Answer 1

2.
$49 {x}^{2} - 81 {y}^{2} \\ = (7x - 9y)(7x + 9y)$
$\frac{1}{64} {x}^{2} - 121 = \\ (\frac{1}{8} x - 11)( \frac{1}{8} x + 11)$
$\frac{1}{9} {x}^{2} - \frac{4}{16} {y}^{2} = \\ ( \frac{1}{3} x - \frac{2}{4} y)( \frac{1}{3} x + \frac{2}{4} y)$
3.
$4 {y}^{2} + 81 = 0$
Поскольку левая часть всегда >0 уравнение не имеет решений
$28 - {x}^{2} = 3 \\ {x}^{2} = 28 - 3 = 25 \\ x1 =5 \\ x2 = - 5$
$4z - 64z {}^{2} =0 \\ 4z(1 - 16z) = 0 \\ 4z = 0 \\ z1 = 0$
$1 - 16z = 0 \\ 16z = 1 \\ z2 = \frac{1}{16}$
${y}^{2} - 19 = 0 \\ {y}^{2} = 19 \\ y1 = - \sqrt{19} \\ y2 = \sqrt{19}$
${z}^{2} - 5 = 0 \\ {z}^{2} = 5 \\ z1 = \sqrt{5 } \\ x2 = - \sqrt{5}$
4.
$25 = {5}^{2} \\ 169 = {13}^{2} \\ 6400 = {80}^{2}$
$17 = \sqrt{17} \\ 9 = {3}^{2} \\ 90000 = {300}^{2} \\ 15 = \sqrt{15}$
5.
$- \frac{24}{7} + 1 \frac{2}{21} = - 3 \frac{3}{7} + 1 \frac{2}{21} = \\ - 3 \frac{9}{21} + 1 \frac{2}{21} = - 2 \frac{7}{21} = - 2 \frac{1}{3}$
$- 1 \frac{2}{3} \times ( - 2 \frac{1}{3} ) = \frac{5}{3} \times \frac{7}{3} = \frac{35}{9} = \\ 3 \frac{8}{9}$
2)
$- 1 \frac{1}{14} - 2 \frac{2}{35} = - 1 \frac{5}{70} - 2 \frac{4}{70} = \\ - 2 \frac{4}{70} - 1 \frac{5}{70} = - 1 \frac{74}{70} - 1 \frac{5}{70} =$
$= - 2 \frac{79}{70} = - 3 \frac{9}{70} \\ - 2 \frac{5}{7} \div ( - 3 \frac{9}{70} ) = \frac{19}{7} \div \frac{219}{70}$
$\frac{19}{7} \times \frac{70}{219} = \frac{190}{219}$