1) 6х(6х-4) +9х(3-4х) = 36х²-24х+27х-36х² = 3х
х(-1/9) = 3×(-1/9) = -1/3
2) 2m(m-n) - n(3m-n) - n(n+6) = 2m²-2mn-3mn +n²-n²-6n = 2m²-5mn-6n
m = -4, n = 0.5
2×(-4)²- 5(-4)×0.5 - 6×0.5 = 39
Меньшую сторону принимаем за х, большую за 11х. Периметр = сумме всех сторон. (х + 11х) умножить на 2 = 144, 12х = 144/2=72, х=72/12=6. Меньшая сторона = 6, большая = 6 умножить на 11= 66 Ответ: 1 сторона = 6 см, 2 сторона = 66см
( 6c - 5)(6c + 5) - (6c - 5)² = 36c² - 25 - (36c² - 60c + 25) = 36c² - 36c² - 25 - 25 + 60c=
= 60c - 50
При c = 11:
60c - 50 = 60×11 - 50 = 660 - 50 = 610.
1.
![9 \sqrt{2} - 3 \sqrt{25 \times 2} + 2 \sqrt{8 \times 16 } \\ = 9 \sqrt{2} - 3 \times 5 \sqrt{2} + 2 \times 4 \sqrt{8} \\ = 9 \sqrt{2 } - 15\sqrt{2} + 8 \sqrt{2 \times 4} =](https://tex.z-dn.net/?f=9+%5Csqrt%7B2%7D++-+3+%5Csqrt%7B25+%5Ctimes+2%7D++%2B+2+%5Csqrt%7B8+%5Ctimes+16+%7D++%5C%5C++%3D+9+%5Csqrt%7B2%7D++-+3+%5Ctimes+5+%5Csqrt%7B2%7D++%2B+2+%5Ctimes+4+%5Csqrt%7B8%7D++%5C%5C++%3D+9+%5Csqrt%7B2+%7D++-+15%5Csqrt%7B2%7D++%2B+8+%5Csqrt%7B2+%5Ctimes+4%7D++%3D+)
![= 9 \sqrt{2} - 15 \sqrt{2} + 8 \times 2 \sqrt{2} = \\ 9 \sqrt{2} - 15 \sqrt{2} + 16 \sqrt{2} = 10 \sqrt{2}](https://tex.z-dn.net/?f=+%3D+9+%5Csqrt%7B2%7D++-+15+%5Csqrt%7B2%7D++%2B+8+%5Ctimes+2+%5Csqrt%7B2%7D++%3D++%5C%5C+9+%5Csqrt%7B2%7D++-+15+%5Csqrt%7B2%7D++%2B+16+%5Csqrt%7B2%7D++%3D+10+%5Csqrt%7B2%7D+)
2.
![{2x}^{2} - 15x + 7 = 0](https://tex.z-dn.net/?f=+%7B2x%7D%5E%7B2%7D++-+15x+%2B+7+%3D+0)
D=
![{ (- 15)}^{2} - 4 \times 2 \times 7 = 225 - 56 = \\ 169 = {13}^{2}](https://tex.z-dn.net/?f=+%7B+%28-+15%29%7D%5E%7B2%7D++-+4+%5Ctimes+2+%5Ctimes+7+%3D+225+-+56+%3D+%5C%5C++169+%3D++%7B13%7D%5E%7B2%7D+)
![x1 = \frac{15 + 13}{2 \times 2} = \frac{28}{4} = 7 \\ x2 = \frac{15 - 13}{4} = \frac{2}{4} = 0.5](https://tex.z-dn.net/?f=x1+%3D++%5Cfrac%7B15+%2B+13%7D%7B2+%5Ctimes+2%7D++%3D++%5Cfrac%7B28%7D%7B4%7D++%3D+7+%5C%5C+x2+%3D++%5Cfrac%7B15+-+13%7D%7B4%7D++%3D++%5Cfrac%7B2%7D%7B4%7D++%3D+0.5)
Найдём сумму корней уравнения
7+0,5=7,5