Question

помогите пж с алгеброй 55 баллов​

Answer 1

$1)\left \{ {{2x+y=5} \atop {y+x=7}} \right.\\\\\left \{ {{2x+y=5} \atop {x+y=7}|*(-1)} \right. \\\\+\left \{ {{2x+y=5} \atop {-x-y=-7}} \right. \\-------\\x=-2\\\\y=7-x=7-(-2)=7+2=9\\\\Otvet:\boxed{(-2;9)}$

$2)y=5x-3\\\\\boxed{x \in R}\\\\3)y=\frac{x}{x-5}\\\\x-5\neq0\\\\x\neq 5\\\\Otvet:\boxed{x\in(-\infty;5)\cup(5;+\infty)}$

$4)y=\frac{4x+2}{3}\\ -2\leq x\leq7\\\\y(-2)=\frac{4*(-2)+2}{3}=\frac{-8+2}{3}=-2\\\\y(7)=\frac{4*7+2}{3}=\frac{28+2}{3}=10\\\\Otvet:\boxed{-2\leq y\leq 10}$