19х-12х=4,9
7х=4,9
х=4,9:7
х=0,7
0.3x^2 - 9x = 0
x(0.3x - 9) = 0
x = 0, или 0.3x-9 = 0
0.3x = 9
x = 30
![y = x*\frac{46}{5} - (x-5)*\frac{6}{5}\\\\ y(0) = 0 - (-5)*\frac{6}{5} = 6\\\\ y(5) = 5*\frac{46}{5} - 0 = 46](https://tex.z-dn.net/?f=y+%3D+x%2A%5Cfrac%7B46%7D%7B5%7D+-+%28x-5%29%2A%5Cfrac%7B6%7D%7B5%7D%5C%5C%5C%5C+y%280%29+%3D+0+-+%28-5%29%2A%5Cfrac%7B6%7D%7B5%7D+%3D+6%5C%5C%5C%5C+y%285%29+%3D+5%2A%5Cfrac%7B46%7D%7B5%7D+-+0+%3D+46)
Уравнение можно преобразовать к такому виду:
![y = x*\frac{46}{5} - (x-5)*\frac{6}{5} | * 5\\\\ 5y = 46x - 6(x-5)\\\\ 5y = 40x +30 | : 5\\\\y = 8x + 6](https://tex.z-dn.net/?f=+y+%3D+x%2A%5Cfrac%7B46%7D%7B5%7D+-+%28x-5%29%2A%5Cfrac%7B6%7D%7B5%7D+%7C+%2A+5%5C%5C%5C%5C+5y+%3D+46x+-+6%28x-5%29%5C%5C%5C%5C+5y+%3D+40x+%2B30+%7C+%3A+5%5C%5C%5C%5Cy+%3D+8x+%2B+6)
Первоначальное уравнение было найденно таким способом:
![y = (x - x_1)\frac{y_2}{x_2-x_1} + (x - x_2)\frac{y_1}{x_1-x_2}](https://tex.z-dn.net/?f=y+%3D+%28x+-+x_1%29%5Cfrac%7By_2%7D%7Bx_2-x_1%7D+%2B+%28x+-+x_2%29%5Cfrac%7By_1%7D%7Bx_1-x_2%7D)
Sin³α + cos³α = (sinα+cosα)(sin²α-sinα*cosα+cos²α) =
= 1/2 *( 1-sinαcosα).
Для определения произведения синуса и сосинуса возведем в квадрас их сумму.
(sinα+cosα)² = sin²α+2sinα*cosα + cos²α = 1+ 2sinα*cosα.
1/4 = 1 + 2sinα*cosα.⇒sinα*cosα = -3/8.
Вычисляем ответ: 1/2*(1+3/8) = 11/16.
(3b^8c^7)³ * (8b³c³)^0 / (27b³c³)²=
=(3³b^24c^21 *1 ) / ( 3^6b^6C^6) =
=(1/27) * b^18c^15