Задача 55008 {xy=80 {4x–3y=16...

5f6cf18a347ae046112d5363

26.10.2020 22:23:20

{xy=80
{4x–3y=16

5f3ea7e3faf909182968ddd9

26.10.2020 23:01:04

Способ подстановки:
[m]\left\{\begin{matrix}\frac{16+3y}{4}\cdot y=80\\ x=\frac{16+3y}{4}\end{matrix}\right.[/m] [m]\left\{\begin{matrix}3y^2+16y-320=0\\ x=\frac{16+3y}{4}\end{matrix}\right.[/m]

D=256+3840=4096=64^2


[m]\left\{\begin{matrix}
y_{1}=8\\ x_{1}=10\end{matrix}\right.[/m] или[m]\left\{\begin{matrix}
y_{2}=-\frac{40}{3}\\ x_{2}=-6\end{matrix}\right.[/m]