![1) \frac{x-7}{ \sqrt{x-7} } =\frac{ \sqrt{x-7} ^2}{ \sqrt{x-7} }= \sqrt{x-7} \\ \\ \\ \\ 2)\frac{x-7}{x+3}= \frac{x-6}{x+24} \\ \\ (x-7)(x+24)=(x-6)(x+3) \\ \\ x^{2} +17x-168= x^{2} -3x-18 \\ \\ 17x+3x=-18+168 \\ \\ 20x=150 \\ \\ x=7.5](https://tex.z-dn.net/?f=1%29+%5Cfrac%7Bx-7%7D%7B+%5Csqrt%7Bx-7%7D+%7D+%3D%5Cfrac%7B+%5Csqrt%7Bx-7%7D+%5E2%7D%7B+%5Csqrt%7Bx-7%7D+%7D%3D+%5Csqrt%7Bx-7%7D++%5C%5C++%5C%5C+++%5C%5C++%5C%5C+2%29%5Cfrac%7Bx-7%7D%7Bx%2B3%7D%3D+%5Cfrac%7Bx-6%7D%7Bx%2B24%7D+%5C%5C++%5C%5C+++%28x-7%29%28x%2B24%29%3D%28x-6%29%28x%2B3%29+%5C%5C++%5C%5C++x%5E%7B2%7D+%2B17x-168%3D+x%5E%7B2%7D+-3x-18+%5C%5C++%5C%5C+17x%2B3x%3D-18%2B168+%5C%5C++%5C%5C+20x%3D150+%5C%5C++%5C%5C+x%3D7.5)
![\left \{ {{x-y=3} \atop {2 x^{2} +y^2=9}} \right. \\ \\ \left \{ {{x=y+3} \atop {2 (y+3)^{2} +y^2=9}} \right. \\ \\ 2 y^{2} +12y+18+ y^{2} =9 \\ \\ 3y^{2} +12y+9=0 \\ \\ y^{2} +4y+3=0 \\ \\ D=4^2-4*3=4 \\ \\ y_1= \frac{-4+2}{2}=-1 \\ \\ y_2= \frac{-4-2}{2}=-3 \\ \\ x_1=-1+3=2 \\ \\ x_2=-3+ 3=0](https://tex.z-dn.net/?f=+%5Cleft+%5C%7B+%7B%7Bx-y%3D3%7D+%5Catop+%7B2+x%5E%7B2%7D+%2By%5E2%3D9%7D%7D+%5Cright.+%5C%5C++%5C%5C+++%5Cleft+%5C%7B+%7B%7Bx%3Dy%2B3%7D+%5Catop+%7B2+%28y%2B3%29%5E%7B2%7D+%2By%5E2%3D9%7D%7D+%5Cright.+%5C%5C++%5C%5C++2+y%5E%7B2%7D+%2B12y%2B18%2B+y%5E%7B2%7D+%3D9+%5C%5C++%5C%5C+3y%5E%7B2%7D+%2B12y%2B9%3D0+%5C%5C++%5C%5C++y%5E%7B2%7D+%2B4y%2B3%3D0+%5C%5C++%5C%5C+D%3D4%5E2-4%2A3%3D4+%5C%5C++%5C%5C+y_1%3D+%5Cfrac%7B-4%2B2%7D%7B2%7D%3D-1+%5C%5C++%5C%5C+y_2%3D+%5Cfrac%7B-4-2%7D%7B2%7D%3D-3+%5C%5C++%5C%5C+x_1%3D-1%2B3%3D2+%5C%5C++%5C%5C+x_2%3D-3%2B+3%3D0+)
5. x≥3
x≤7
\\\\\\\\\\\\\\\\\\\\\\\\
__________3___________7__________
x∈[3; 7]
6.
![a_1=17 d=-8 a_{11}=a_1+d(11-1)=17+(-8)*10=-63](https://tex.z-dn.net/?f=a_1%3D17%0Ad%3D-8%0Aa_%7B11%7D%3Da_1%2Bd%2811-1%29%3D17%2B%28-8%29%2A10%3D-63)
Скорость по течению 720/36=20 км/ч, скорость против течения 720/45=16 км/ч
скорость течения (20-16)/2=2 км/ч, значит скорость теплохода = 20-2=18 км/ч
А) 60 шагов, 3600 шагов
б) 10 000*90=900 000 см=900 м=0,9 км
в) 1260 км
А) = 7/14 + 10/14 = 17/14 = 1 3/14
б) = 24/30 + 5/30 = 29/30
в) = 3/6 - 2/6 = 1/6
г) = 4/12 - 3/12 = 1/12
д) = 10/15 - 3/15 = 7/15
е) = 15/21 - 14/21 = 1/21