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Alesyaperova_zn · Answer 1 · 2020-05-27T17:04:24+0000

70.
1. Имеет
2.имеет
3.не имеет
4. Имеет
71.
$1)0.1 \times 30 - \frac{1}{4} \times 8 = 3 - 2 = 1 \\ 2)5 \times 0.2 + \sqrt{27 + 22} = 1 + \sqrt{49} \\ = 1 + 7 = 8$
$3)4 \times 0.7 - \sqrt{289} = 2.8 - 17 = \\ - 14.2 \\$
$4) \sqrt{ \frac{100}{49} } + \sqrt{ \frac{25}{9} } - 0.03 \times 200 = \\ \frac{10}{7} + \frac{5}{3} - 6 = 1 \frac{3}{7} + 1 \frac{2}{ 3} - 6 =$
$1 \frac{9}{21} + 1 \frac{14}{21} = 2 \frac{23}{21} = 3 \frac{2}{21} - 6 = \\ 3 \frac{2}{21} - 5 \frac{21}{21} = - 2 \frac{19}{21}$
72.
$1)7 - 1.1 = 5.9 \\ 2)48 - 45 = 3 \\ 3)32 \times ( - \frac{1}{4} \times 11) - \frac{1}{3} \times 735 =$
$32 \times ( - \frac{11}{4} ) - 245 = \\ - 88 - 245 = - 333$
$4)28 - \frac{1}{49} \times 343 = 28 - 7 = 21$
73.
1)при а=9
2)при а=3
3)при а =5
4)не знаю
5)при а =-5
6)не знаю
74.
$1) \sqrt{x } = 7 \\ x = 49 \\ 2) \sqrt{x} = \frac{4}{5}$
$x = \frac{16}{25}$
$3) \sqrt{x} = 5 \\ x = 25$
$4)3 \sqrt{x} = 8 \\ \sqrt{x} = 8 \div 3 = \frac{8}{3} \\ x = \frac{64}{9} = 7 \frac{1}{9}$
$5) \frac{1}{2} \sqrt{x} = - 3 \\ \sqrt{x} = - 3 \div \frac{1}{2} = - 6 \\$
Нет решения
$6) \sqrt{5x} = 6 \\ 5x = 36 \\ x = 36 \div 5 = 7.2$
$7)5x - 6 = 0 \\ 5x = 6 \\ x = 6 \div 5 \\ x = 1.2$
$8)5x - 6 = 1 \\ 5x = 1 + 6 = 7 \\ x = 7 \div 5 = 1.4$
$9) 24 = 12 \sqrt{x} \\ \sqrt{x} = 24 \div 12 = 2 \\ x = 4$
Умножили обе части на корень из х
$10)12 = 4( \sqrt{x - 3} ) \\ 4 \sqrt{x} - 12 = 12 \\ 4 \sqrt{x } = 12 + 12 = 24 \\ \sqrt{x} = 24 \div 4 = 6 \\ x =$
$x = 36$
$11)2 + \sqrt{2 + \sqrt{x} } = 4 \\ \sqrt{2 + \sqrt{x} } = 4 - 2 = 2 \\ 2 + \sqrt{x} = 4 \\$
$\sqrt{x} = 4 - 2 = 2 \\ x = 4$
$12)2 \sqrt{ {x}^{2} - 9} = - x \\ 4( {x}^{2} - 9) = {x}^{2} \\ 4 {x}^{2} - 36 - {x}^{2} = 0 \\ 3 {x}^{2} = 36 \\ {x}^{2}$
${x}^{2} = 12 \\ x = - + \sqrt{4 \times 3} = - + 2 \sqrt{3}$
75.
$1)x = + - 3 \\ 2)x = + - \sqrt{13}$
$3) {x}^{2} + 2x + 1 = 0 \\ d = 4 - 4 = 0 \\ x = \frac{ - 2 - 0}{2} = - 1$
Либо
$x + 1 = 0 \\ x = - 1$
4)нет решения
$5) {x}^{2} - 4x + 4 - 64 = 0 \\ {x}^{2} - 4x - 60 = 0 \\ d = 16 + 240 = 256 = 16$
$x1 = \frac{4 + 16}{2} = \frac{20}{2} = 10 \\ x2 = \frac{4 - 16}{2} = - \frac{12}{2} = - 6$
$6) {x}^{2} + 10x + 25 - 2 = 0 \\ {x}^{2} + 10x + 23 = 0 \\ d = 100 - 92 = 8 = 2 \sqrt{2}$
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