Question

Быстрей пж алгебра 8 класс даю 71б

Answer 1

Ответ:

Объяснение:

1-Б

$\displaystyle\\\\\[\frac{4}{x} - \frac{5}{{{x^2}}} = \frac{{4x}}{{{x^2}}} - \frac{5}{{{x^2}}} = \frac{{4x - 5}}{{{x^2}}}\]$

2-Г

$\displaystyle\\\[\frac{{5x + 6}}{{x - 5}} - \frac{{3x + 16}}{{x - 5}} = \frac{{5x + 6 - (3x + 16)}}{{x - 5}} = \frac{{5x + 6 - 3x - 16)}}{{x - 5}} = \frac{{2x - 10}}{{x - 5}} = \frac{{2(x - 5)}}{{x - 5}} = 2\]$

3-В

$\displaystyle\\\[\frac{1}{{{x^2} + 5x}} + \frac{1}{{5x + 25}} = \frac{1}{{x(x + 5)}} + \frac{1}{{5(x + 5)}} = \frac{5}{{5x(x + 5)}} + \frac{x}{{5x(x + 5)}} = \frac{{x + 5}}{{5x(x + 5)}} = \frac{1}{{5x}}\]$

4-А

$\displaystyle\\\[\frac{{7x + 5}}{{1 - 3x}} + \frac{{4x + 6}}{{3x - 1}} = \frac{{(7x + 5) \cdot ( - 1)}}{{(1 - 3x) \cdot ( - 1)}} + \frac{{4x + 6}}{{3x - 1}} = \frac{{ - 7x - 5}}{{3x - 1}} + \frac{{4x + 6}}{{3x - 1}} = \frac{{ - 7x - 5 + 4x + 6}}{{3x - 1}} = \frac{{1 - 3x}}{{3x - 1}} = \frac{{ - 1 \cdot (3x - 1)}}{{3x - 1}} = - 1\]$