Question

Решите систему:
3х+4у=-1
2х+5у=4

Answer 1

х=2у-3
3х+4у=1
1)3(2у-3)+4у=1
6у-9+4у=1
10у=10
у=1
2) х=2у-3
х=2*1-3
х=-1

Answer 2

$\left \{ {{3x+4y=-1|(*2)} \atop {2x+5y=4|(*(-3)}} \right. \left \{ {{6x+8y=-2} \atop {-6x-15y=-12}} \right \\ Skladivaem-oba-yravnnija \\ \left \{ {{6x+8y=-2} \atop {-7y=-14}} \right \left \{ {{6x+8y=-2} \atop {y=2} \right \left \{ {{6x+8*2}=-2} \atop {y=2} \right \left \{ {{6x=-2-8*2} \atop {y=2} \right.\left \{ {{6x=-2-16} \atop {y=2} \right\left \{ {{6x=-18} \atop {y=2} \right.\left \{ {{x=-3} \atop {y=2}$
Ответ:(-3; 2)