решите систему уравнений:
1)3x+7y=-4
5x-8y=13;
2)4x-5y=12
6x+11y=-19;
3)2x+9y-2=0
8x-15y-25=0;

1)3x+7y=-4/*8⇒24x+56y=-32 5x-8y=13/*7⇒35x-56y=9159x=59x=13+7y=-47y=-7y=-1(1;-1) 2)4x-5y=12/11⇒44x-55y=132 6x+11y=-19/*5⇒30x+55y=-9574x=37y=0,54x-2,5=124x=14,5x=3,625(3,625;0,5) 3)2x+9y-2=0/*-4⇒-8x-36y+8=0 8x-15y-25=0-51y-17=0-51y=17y=-1/32x-3-2=02x=5x=2,5(2,5;-1/3)