(40-y)·6=30·5
240-6y=150
-6y=-240+150
-6y=-90
6y=90
y=90:6
y=15
Х
у
х=у+8
х+6*х-8=72
х^2 - 8x +6x-48-72=0
x^2-2x-120=0
d=4+480=484
x1;2= 2+-22 / 2
x1= 22
x2=-10
22-8=14
22+8=30
Ответ:
![a=\pm1.5](https://tex.z-dn.net/?f=a%3D%5Cpm1.5)
Объяснение:
Один из корней уравнения x^2-4ax+8=0 на 2 больше другого. Найдите а.
по теореме Виета
x₁*x₂=8
x₁+x₂=4a ⇒ x₂=x₁+2
![\displaystyle\\\left \{ {{x_1(x_1+2)=8} \atop {x_1+(x_1+2)=4a}} \right. \\\\\\\left \{ {{x_1^2+2x_1=8} \atop {2x_1+2=4a}} \right.\\\\\\ \left \{ {{x_1^2+2x_1=8} \atop {x_1=2a-1}} \right.\\\\\\(2a-1)^2+2(2a-1)=8\\\\4a^2-4a+1+4a-2-8=0\\\\4a^2=9\\\\a^2=\frac{9}{4}\\\\a=\pm\frac{3}{2} \\\\Otvet:a=\pm1.5](https://tex.z-dn.net/?f=%5Cdisplaystyle%5C%5C%5Cleft%20%5C%7B%20%7B%7Bx_1%28x_1%2B2%29%3D8%7D%20%5Catop%20%7Bx_1%2B%28x_1%2B2%29%3D4a%7D%7D%20%5Cright.%20%5C%5C%5C%5C%5C%5C%5Cleft%20%5C%7B%20%7B%7Bx_1%5E2%2B2x_1%3D8%7D%20%5Catop%20%7B2x_1%2B2%3D4a%7D%7D%20%5Cright.%5C%5C%5C%5C%5C%5C%20%5Cleft%20%5C%7B%20%7B%7Bx_1%5E2%2B2x_1%3D8%7D%20%5Catop%20%7Bx_1%3D2a-1%7D%7D%20%5Cright.%5C%5C%5C%5C%5C%5C%282a-1%29%5E2%2B2%282a-1%29%3D8%5C%5C%5C%5C4a%5E2-4a%2B1%2B4a-2-8%3D0%5C%5C%5C%5C4a%5E2%3D9%5C%5C%5C%5Ca%5E2%3D%5Cfrac%7B9%7D%7B4%7D%5C%5C%5C%5Ca%3D%5Cpm%5Cfrac%7B3%7D%7B2%7D%20%5C%5C%5C%5COtvet%3Aa%3D%5Cpm1.5)