Question

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;

Answer 1

1)3x+7y=-4/*8⇒24x+56y=-32
5x-8y=13/*7⇒35x-56y=91
59x=59
x=1
3+7y=-4
7y=-7
y=-1
(1;-1)
2)4x-5y=12/11⇒44x-55y=132
6x+11y=-19/*5⇒30x+55y=-95
74x=37
y=0,5
4x-2,5=12
4x=14,5
x=3,625
(3,625;0,5)
3)2x+9y-2=0/*-4⇒-8x-36y+8=0
8x-15y-25=0
-51y-17=0
-51y=17
y=-1/3
2x-3-2=0
2x=5
x=2,5
(2,5;-1/3)