Раскрываем скобки:
-4х^2y^2-6xy^2-2x^2y+2xy^2+3y^2+xy=-4x^2y^2-4xy^2-2x^2y+3y^2+xy
А) площадь 9 периметр 36
б) площадь 13.69 периметр 14.8
![\frac{x}{x + 5} + \frac{x + 5}{x - 5} = \frac{50}{ {x}^{2} - 25 }](https://tex.z-dn.net/?f=+%5Cfrac%7Bx%7D%7Bx+%2B+5%7D++%2B++%5Cfrac%7Bx+%2B+5%7D%7Bx+-+5%7D++%3D++%5Cfrac%7B50%7D%7B+%7Bx%7D%5E%7B2%7D+-+25+%7D+)
ОДЗ: х не равно +-5
Умножим в левой части первую дробь на х-5, а вторую - на х+5
![\frac{x(x - 5) + {(x + 5)}^{2} }{ {x}^{2} - 25 } = \frac{50}{ {x}^{2} - 25 } \: \: \: \: \: ( \times ({x}^{2} - 25)) \\ {x}^{2} - 5x + {x}^{2} + 10x + 25 = 50 \\ 2 {x}^{2} + 5x - 25 = 0 \\ D = 25 + 200 = 225 = 15 \\ x 1 = \frac{ - 5 + 15}{4} = \frac{10}{4} = 2.5 \\ x2 = \frac{ - 5 - 15}{4} = - 5](https://tex.z-dn.net/?f=+%5Cfrac%7Bx%28x++-+5%29+%2B++%7B%28x+%2B+5%29%7D%5E%7B2%7D+%7D%7B+%7Bx%7D%5E%7B2%7D+-+25+%7D++%3D++%5Cfrac%7B50%7D%7B+%7Bx%7D%5E%7B2%7D+-+25+%7D++%5C%3A++%5C%3A+++%5C%3A++%5C%3A++%5C%3A+%28+%5Ctimes++%28%7Bx%7D%5E%7B2%7D+-+25%29%29+%5C%5C++%7Bx%7D%5E%7B2%7D++-+5x+%2B++%7Bx%7D%5E%7B2%7D++%2B+10x+%2B+25+%3D+50+%5C%5C+2+%7Bx%7D%5E%7B2%7D++%2B+5x+-+25+%3D+0+%5C%5C+D+%3D+25+%2B+200+%3D+225+%3D+15+%5C%5C+x+1+%3D++%5Cfrac%7B+-+5+%2B+15%7D%7B4%7D++%3D++%5Cfrac%7B10%7D%7B4%7D++%3D+2.5+%5C%5C+x2+%3D++%5Cfrac%7B+-+5+-+15%7D%7B4%7D++%3D++-+5)
Ответ: х=2.5
1. 4 - x = 0; x = 4
2. x + 6 = 0; x = -6
3. x - 5 = 0; x = 5
(x ⩾ 5)!
ОТВЕТ: 5