Question

2x+y=7 3x-y=0


Чему равен x? ​

Answer 1

$\left \{ {{2x+y=7} \atop {3x-y=0} \right. \left \{ {y=7-2x} \atop {3x-y=0} \right. \\\\3x-(7-2x)=0\\x=\frac{7}{5}\\y=7-2*\frac{7}{5}\\y = \frac{21}{5}$

Answer 2

1 способ:

{2х+у=7

{3х-у=0 => у=3х

2х+3х=7

5х=7

х=7/5=1,4

2способ:

{2х+у=7

{3х-у=0

прибавляем уравнения:

5х+0=7

5х=7

х=7/5=1,4