a)
![5x^2+x=0\\ x(5x+1)=0\\ \\ \left \{ {{x_1=0} \atop {5x+1=0}} \right. =>\left \{ {{x_1=0} \atop {x_2=-\frac{1}{5} }} \right.](https://tex.z-dn.net/?f=5x%5E2%2Bx%3D0%5C%5C+x%285x%2B1%29%3D0%5C%5C+%5C%5C+%5Cleft+%5C%7B+%7B%7Bx_1%3D0%7D+%5Catop+%7B5x%2B1%3D0%7D%7D+%5Cright.+%3D%3E%5Cleft+%5C%7B+%7B%7Bx_1%3D0%7D+%5Catop+%7Bx_2%3D-%5Cfrac%7B1%7D%7B5%7D+%7D%7D+%5Cright.)
б)
![(6-3x)^2=4x-8\\36-36x+9x^2-4x+8=0\\ 44-40x+9x^2=0\\ 9x^2-40x+44=0\\ 9x^2-18x-22x+44=0\\ 9x(x-2)-22(x-2)=0\\(x-2)(9x-22)=0\\\\\left \{ {{x-2=0} \atop {9x-22=0}} \right. =>\left \{ {{x_1=2} \atop {x_2=\frac{22}{9} }} \right.](https://tex.z-dn.net/?f=%286-3x%29%5E2%3D4x-8%5C%5C36-36x%2B9x%5E2-4x%2B8%3D0%5C%5C+44-40x%2B9x%5E2%3D0%5C%5C+9x%5E2-40x%2B44%3D0%5C%5C+9x%5E2-18x-22x%2B44%3D0%5C%5C+9x%28x-2%29-22%28x-2%29%3D0%5C%5C%28x-2%29%289x-22%29%3D0%5C%5C%5C%5C%5Cleft+%5C%7B+%7B%7Bx-2%3D0%7D+%5Catop+%7B9x-22%3D0%7D%7D+%5Cright.+%3D%3E%5Cleft+%5C%7B+%7B%7Bx_1%3D2%7D+%5Catop+%7Bx_2%3D%5Cfrac%7B22%7D%7B9%7D+%7D%7D+%5Cright.)
можно было решить дискриминантом
в)
![2x^3-10x^2+3x-15=0\\2x^2(x-5)+3(x-5)=0\\(x-5)(2x^2+3)=0\\\\x-5=0\\x_1=5\\\\2x^2=-3\\x \in \emptyset\\\\x=5](https://tex.z-dn.net/?f=2x%5E3-10x%5E2%2B3x-15%3D0%5C%5C2x%5E2%28x-5%29%2B3%28x-5%29%3D0%5C%5C%28x-5%29%282x%5E2%2B3%29%3D0%5C%5C%5C%5Cx-5%3D0%5C%5Cx_1%3D5%5C%5C%5C%5C2x%5E2%3D-3%5C%5Cx+%5Cin+%5Cemptyset%5C%5C%5C%5Cx%3D5)
4) х²/у² + 2х/у + 1 = х²/у² + 2ху/у² + 1 = (х²+2ху)/у² + 1 = <span>(х²+2ху)/у² + у</span>²<span>/у</span>² =
(х²+2ху+у²)/у² = (х+у)²/у².
5) р/(р-2) + 1= р/(р-2) + (р-2)/(р-2)= (р+р-2)/(р-2)= (2р-2)/(р-2) = 2(р-1)/(р-2).
6) р + р²/(2-р) = (2р-р²)/(2-р) + р²/(2-р) = (2р-р²+р²)/(2-р) = 2р/(2-р).
7) х²/у² + 2х/у + 1 = х²/у² + 2ху/у² + 1 = (х²+2ху)/у² + 1 = (х²+2ху)/у² + у²/у² =
(х²+2ху+у²)/у² = (х+у)²/у².
Решение:
Составим пропорцию, но прежде переведём 7 мин 12 секунд в секунды
7мин 12 сек=432сек
432 х 40\%
х - 100\%
х=432*100/40=1080 (сек) или 18 мин
Ответ: 18 мин
150*24 это под корнем выходит 3600 из корня это 60