Question

12.19(б)
{6х+3 = 8х-3(2у-4)
2(2х-3у )-4х =2у-8

12.21 (в)

{ 3х+2у          х-3у
-------- +        ---------- =3
5                      6

Answer 1

$left { {{6x+3=8x-6y+12} atop {4x-6y-4x=2y-8}} right. => left { {{-2x+6y=9} atop {-8y=-8 => y=1}} right. -2x+6*1=9 \ -2x=9-6 \ -2x=3 \ x=-1,5 \ (-1,5;1)$

$left { {{ frac{3x+2y}{5} + frac{x-3y}{6} =3|*30} atop {2x+7y+43=0}} right. => left { {{ 6(3x+2y)+5(x-3y)=90} atop {2x+7y+43=0}} right. => \ left { {{ 18x+12y+5x-15y=90} atop {2x+7y+43=0}} right. =>left { {{ 23x-3y=90|*7} atop {2x+7y=-43|*3}} right. => \ +left { {{ 161x-21y=630} atop {6x+21y=-129}} right. 167x=501=>x=3 \ 2*3+7y=-43 \ 7y=-43-6 \ 7y=-49 \ y=-7 \ (3;-7)$

Answer 2

это 1 задание? или как