Question

Решить методом подстановки: y+х=2;
2y-2х=5

Answer 1

$\left\{{{y+x=2}\atop{2y-2x=5}}\right.\\\left\{{{2y+2x=4}\atop{2y-2x=5}}\right.\\ \left\{{{2y=4-2x}\atop{4-2x-2x=5}}\right.\\ \left\{{{2y=4-2x}\atop{4-4x=5}}\right.\\ -4x=1\\ x=-\frac{1}{4}\\ y=2-x=2+\frac{1}{4}=2.25\\ Ans:(-0.25;2.25)$

Answer 2

y+x=2
y=2-x
y=2-x

2y-2x=52y=5+2x
y=5/2+x
y=5/2