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)
$- 1 frac{1}{14} - 2 frac{2}{35} = - 1 frac{5}{70} - 2 frac{4}{70} = \ - 2 frac{4}{70} - 1 frac{5}{70} = - 1 frac{74}{70} - 1 frac{5}{70} =$
$= - 2 frac{79}{70} = - 3 frac{9}{70} \ - 2 frac{5}{7} div ( - 3 frac{9}{70} ) = frac{19}{7} div frac{219}{70}$
$frac{19}{7} times frac{70}{219} = frac{190}{219}$