Question

Sa se rezolve sistemul :
8x+5y=21
{
-3x+4y=-2

Answer 1

{8x+5y=21 |•3
{-3x+4y=-2 |•8
<=>{24x+15y=63
{-24x+32y=-16
------------------------------
/47y=47
y=1
<=>{y=1
{8x+5•1=21
<=>{y=1
{8x+5=21 |-5
<=>{y=1
{8x=16
<=>{y=1
{x=2

Answer 2

8x+5y=21 |•(-4). -32x-20y=-84
} = > } =>
-3x+4y=-2|•(+5). -15x+20y=-10
(+) -47x \ = -94 =>
-47x=-94 => x = (-94):(-47) = -2
-3•(-2)+4y= -2 => -6+4y= -2=> 4y= -2+6=4 => y= 4:4=> y= 1