Question

Системы уравнений. Решите пожалуйста, заранее спасибо)​

Answer 1

$28)\left \{ {{25x-15y=-45}|:5 \atop {21x+2y=6}} \right.\\\\\left \{ {{5x-3y=-9} \atop {2y=6-21x}} \right.\\\\\left \{ {{y=3-10,5x} \atop {5x-3*(3-10,5x)=-9}} \right. \\\\\left \{ {{y=3-10,5x} \atop {5x-9+31,5x=-9}} \right.\\\\\left \{ {{y=3-10,5x} \atop {36,5x=0}} \right.\\\\\left \{ {{x=0} \atop {y=3-10,5*0=3}} \right. \\\\Otvet:\boxed{(0;3)}$

$29)+\left \{ {{3x-4y=5} \atop {3x+4y=-1}} \right.\\---------\\6x=4\\\\x=\frac{2}{3} \\\\-\left \{ {{3x-4y=5} \atop {3x+4y=-1}} \right. \\-------\\-8y=6\\\\y=-0,75\\\\Otvet:\boxed{(\frac{2}{3};-0,75)}$