Question

Нужны ответы на 73 77 79 номера

Answer 1

73 задание.

1)

$\frac{x}{y - 1} + \frac{2}{1 - y} = \frac{x}{y - 1} + \frac{2}{ - (y - 1)} = \frac{x}{y - 1} - \frac{2}{y - 1} = \frac{x - 2}{y - 1}$

2)

$\frac{3c}{c - d} + \frac{3d}{d - c} = \frac{3c}{c - d} + \frac{3d}{ - (c - d)} = \frac{3c}{c - d} - \frac{3d}{c - d} = \frac{3c - 3d}{c - d} = \frac{3(c - d)}{c - d} 3$

3)

$\frac{3m + 2n}{2m - 3n} - \frac{m - 8n}{3n - 2m} = \frac{3m + 2n}{2m - 3n} - \frac{m - 8n}{ - (2m - 3n)} = \frac{3m + 2n}{2m - 3n} + \frac{m - 8n}{ 2m - 3n} = \frac{3m + 2n + m - 8n}{2m - 3n} = \frac{4m - 6n}{2m - 3n} = \frac{2(2m - 3n)}{2m - 3n} = 2$

4)

$\frac{ {b}^{2} }{2b - 14} + \frac{49}{14 - 2b} = \frac{ {b}^{2} }{2b - 14} + \frac{49}{ - (2b - 14)} = \frac{ {b}^{2} }{2b - 14} - \frac{49}{ 2b - 14} = \frac{ {b}^{2} - 49}{2b - 14} = \frac{ {b}^{2} - {7}^{2} }{2(b - 7)} = \frac{(b - 7)(b + 7)}{2(b - 7)} = \frac{b + 7}{2}$

77 задание

1)

$\frac{6a - 1}{16a - 8} + \frac{4a - 7}{16a - 8} + \frac{ - 2a - 2}{8 - 16a} = \frac{6a - 1}{16a - 8} + \frac{4a - 7}{16a - 8} + \frac{ - (2a + 2)}{ - (16a - 8)} = \frac{6a - 1}{16a - 8} + \frac{4a - 7}{16a - 8} + \frac{ 2a + 2}{ 16a - 8} = \frac{6a - 1 + 4a - 7 + 2a + 2}{16a - 8} = \frac{12a - 6}{16a - 8} = \frac{3(4a - 2)}{4(4a - 2)} = \frac{3}{4}$

2)

$\frac{2 {a}^{2} + 12a}{ {a}^{2} - 25 } + \frac{8a - 9}{25 - {a}^{2} } - \frac{ {a}^{2} + 14a - 16}{ {a}^{2} - 25} = \frac{2 {a}^{2} + 12a}{ {a}^{2} - 25 } + \frac{8a - 9}{- ({a}^{2} - 25) }- \frac{ {a}^{2} + 14a - 16}{ {a}^{2} - 25} = \frac{2 {a}^{2} + 12a}{ {a}^{2} - 25 } - \frac{8a - 9}{{a}^{2} - 25 }- \frac{ {a}^{2} + 14a - 16}{ {a}^{2} - 25} = \frac{ 2 {a}^{2} + 12a - 8a + 9 - {a}^{2} - 14a + 16}{{a}^{2} - 25} = \frac{ {a}^{2} - 10a + 25}{ {a}^{2} - {5}^{2} } = \frac{ {(a - 5)}^{2} }{(a - 5)(a + 5)} = \frac{a - 5}{a + 5}$

79 задание

1)

$\frac{ {x}^{2} - 16x}{ {(x - 7)}^{4} } + \frac{2x + 49}{ {(7 - x)}^{4} } = \frac{ {x}^{2} - 16x}{ {(x - 7)}^{4} } + \frac{2x + 49}{ {( - (x - 7))}^{4} } = \frac{ {x}^{2} - 16x}{ {(x - 7)}^{4} } + \frac{2x + 49}{ { (x - 7)}^{4} } = \frac{ {x}^{2} - 16x + 2x + 49 }{ {(x - 7)}^{4} } = \frac{ {x}^{2} - 14x + 49 }{ {(x - 7)}^{4} } = \frac{ {(x - 7)}^{2} }{ {(x - 7)}^{4} } = \frac{1}{ {(x - 7)}^{2} }$

2)

$\frac{ {y}^{2} + y }{(y - 6)(y + 2)} + \frac{y + 36}{(6 - y)(2 + y)} = \frac{ {y}^{2} + y }{(y - 6)(y + 2)} + \frac{y + 36}{ - (y - 6)(y + 2)} = \frac{ {y}^{2} + y }{(y - 6)(y + 2)} - \frac{y + 36}{ (y - 6)(y + 2)} = \frac{ {y}^{2} + y - y - 36}{(y - 6)(y + 2)} = \frac{ {y}^{2} - 36 }{(y - 6)(y + 2)} = \frac{ {y}^{2} - {6}^{2} }{(y - 6)(y + 2)} = \frac{(y - 6)(y + 6)}{(y - 6)(y + 2)} = \frac{y + 6}{y + 2}$