1) [tex]\left \{ {{x=9+2y} \atop {4x+y=o}} \right. [/tex]
2) [tex] \left \{ {{x=y-2 \atop {x+2y=13}} \right.[/tex]
3) [tex] \left \{ {{x+y=36 } \atop {x-y=6}} \right. [/tex]
4) x+3= -3
5
5) x _ 5= 1
4 3 12
a) x - 2y = - 9
4x + y = 0 => y = - 4x => y = - 4(1) => y = - 4
x -2(-4x) = - 9 => x + 8x = 9 => 9x = 9 => x = 1
2)
y - 2 + 2y = 13 => 3y = 13 +2 => 3y = 15 => y = 5
x = 5 - 2 => x = 3
3)
x + y = 36
x - y = 6
2x = 42
x = 42/2 => x = 21
21 + y = 36 => y = 36 - 21 => y = 25
4) x+3= -3
5
x + 3 = - 15
x = - 15 - 3
x = - 18
5) x _ 5= 1 mmc(3,4,12) = 12
4 3 12
3x - 20 = 1
3x = 1 + 20
3x = 21
x= 21/3
x = 7
