Question

помогите пж(((((((((((((((​

Answer 1

1

$-5x-7=0\\-5x=7\\5x=-7\\x=-\frac{7}{5}\\x=-1\frac{2}{5} \\x=-1\frac{4}{10}x=-1,4$

2

$-3x+4=7x\\4 = 7x + 3x\\4 = 10x\\x = \frac{4}{10} \\x = 0,4$

3

$-7-x=3x+17\\-x - 3x = 17 + 7\\-4x = 24\\4x = -24\\x = -\frac{24}{4} \\x = -6$

4

$70 + x = 2(x+9)\\70+x = 2x + 18\\70 - 18 = 2x - x\\52 = x$

5

$\frac{x + 2}{x - 4} = \frac{5}{1}\\ 5(x-4)=x+2\\5x-20=x+2\\4x=22x=\frac{22}{4} x=5,5$

6

$\frac{x - 14}{x - 12} =\frac{7}{8}\\7 * (x-12)=8x-112\\7x - 84 = 8x -112\\-84 + 112 = 8x - 7x\\28=x$

7

$D=b^2 - 4ac = (-8)^2 - 4 * 15 = 64 - 60 = 4\\\sqrt{D} =2\\x = \frac{-b ± \sqrt{D}}{2a}\\x_1 = \frac{8+2}{2} = 5\\x_2 = \frac{8-2}{2} = 3$

8

$-5x^2 + x = 0\\D = b^2 - 4ac = 0^2 - 4*(-5)*0 = 0\\x = \frac{-b}{2a} = \frac{-1}{-10} = 0,1$

13

$x^2 + 3x - 10 = 0\\D = b^2 - 4ac = 3^2 - 4 * (-10) = 9 + 40 = 49\\\sqrt{D} = 7\\x = \frac{-b ± \sqrt{D} }{2a}\\x_1 = \frac{-3 + 7}{2} = 2\\x_2 = \frac{-3 - 7}{2} = -5$

Answer 2

Ответ:

Остальное не знаю как решать