/2х/=1,4
Решение
2х=1,4. 2х=-1,4
х=0,7. х=-0,7
Ответ:х=0,7;х=-0,7
Сделаем замену
![8 ^{ \sqrt{-x} }=m](https://tex.z-dn.net/?f=8%20%5E%7B%20%5Csqrt%7B-x%7D%20%7D%3Dm%20)
>0 ОДЗ: x ≤ 0
Тогда
![64 ^{ \sqrt{-x} }= m^{2}](https://tex.z-dn.net/?f=64%20%5E%7B%20%5Csqrt%7B-x%7D%20%7D%3D%20m%5E%7B2%7D%20%20)
5m² - 17m + 6 = 0
D = (- 17)² - 4 * 5 * 6 = 289 - 120 = 169 = 13²
![m _{1} = \frac{17+13}{10}=3\\\\m _{2} = \frac{17-13}{10}=0,4\\\\8 ^{ \sqrt{-x} }=3\\\\2 ^{3 \sqrt{-x} }=3\\\\3 \sqrt{-x}=log _{2} 3\\\\ \sqrt{-x}= \frac{1}{3}log _{2} 3 \\\\8 ^{ \sqrt{-x} }=0,4\\\\log _{8}8 ^{ \sqrt{-x} }=log _{8} 0,4\\\\ \sqrt{-x}=log _{8}0,4\\\\x=log _{8} 0,4](https://tex.z-dn.net/?f=m%20_%7B1%7D%20%3D%20%5Cfrac%7B17%2B13%7D%7B10%7D%3D3%5C%5C%5C%5Cm%20_%7B2%7D%20%3D%20%5Cfrac%7B17-13%7D%7B10%7D%3D0%2C4%5C%5C%5C%5C8%20%5E%7B%20%5Csqrt%7B-x%7D%20%7D%3D3%5C%5C%5C%5C2%20%5E%7B3%20%5Csqrt%7B-x%7D%20%7D%3D3%5C%5C%5C%5C3%20%5Csqrt%7B-x%7D%3Dlog%20_%7B2%7D%203%5C%5C%5C%5C%20%5Csqrt%7B-x%7D%3D%20%5Cfrac%7B1%7D%7B3%7Dlog%20_%7B2%7D%203%20%5C%5C%5C%5C8%20%5E%7B%20%5Csqrt%7B-x%7D%20%7D%3D0%2C4%5C%5C%5C%5Clog%20_%7B8%7D8%20%5E%7B%20%5Csqrt%7B-x%7D%20%7D%3Dlog%20_%7B8%7D%200%2C4%5C%5C%5C%5C%20%5Csqrt%7B-x%7D%3Dlog%20_%7B8%7D0%2C4%5C%5C%5C%5Cx%3Dlog%20_%7B8%7D%200%2C4%20%20%20%20%20%20%20%20%20%20%20%20)
2) a) c^2+3c-2c-6-2c+2 = c^2-c-4; б) 6a+6c-6ac;
3) a) (4a+3)(4a-3);
Решение:
1) х²- 49 = х² - 7² = ( х - 7)·( х + 7);
<span>2) 25х² - 10 ху + у² = (5х)² - 2·5х·у + у² = ( 5х - у )².</span>
√16 = 4
√4/25 = 2/5
0,5 × 4 = 2
15 × 2/5 = 6
2 - 6 = -4
Ответ: -4