Question

помогите решить систему рівняння ​

Answer 1

Ответ:

$\left \{ {{x=46\frac{1}{2}} \atop {y=-25\frac{1}{2}}$; $\left \{ {{x=6.5} \atop {y=2}} \right.$

Объяснение:

1)

$\left \{ {{\frac{1}{8}(x-y)=9} \atop {\frac{1}{3}(x+y)=7} \right. \\\\\left \{ {{\frac{1}{8}x-\frac{1}{8}y=9} \atop {\frac{1}{3}x+\frac{1}{3}y=7} \right. \\\\\\\left \{ {{\frac{1}{8}x=9+\frac{1}{8}y} \atop {\frac{1}{3}x+\frac{1}{3}y=7} \right.\\\\\\\left \{ {{x=8(9+\frac{1}{8}y)} \atop {\frac{1}{3}x+\frac{1}{3}y=7} \right.\\\\\\\left \{ {{x=72+y} \atop {\frac{1}{3}x+\frac{1}{3}y=7} \right.$

$\left \{ {{x=72+y} \atop {\frac{1}{3}\cdot(72+y)+\frac{1}{3}y=7} \right.\\\\\\\left \{ {{x=72+y} \atop {24+\frac{1}{3}y+\frac{1}{3}y=7} \right.\\\\\\\left \{ {{x=72+y} \atop {24+\frac{2}{3}y=7} \right.\\\\\\\left \{ {{x=72+y} \atop {\frac{2}{3}y=-17} \right.\\\\\\\left \{ {{x=72+y} \atop {y=-17\cdot\frac{3}{2}} \right.\\\\\\\left \{ {{x=72+y} \atop {y=-25\frac{1}{2}} \right.\\\\\\\left \{ {{x=72+(-25\frac{1}{2})} \atop {y=-25\frac{1}{2}} \right.$

$\left \{ {{x=72-25\frac{1}{2}} \atop {y=-25\frac{1}{2}} \right.\\\\\\\left \{ {{x=72-25\frac{1}{2}} \atop {y=-25\frac{1}{2}} \right.\\\\\\\left \{ {{x=46\frac{1}{2}} \atop {y=-25\frac{1}{2}}$

2)

$\left \{ {{0.2(2x+y)=3} \atop {0.7(x-4y)=-1.05}} \right. \\\\\\\left \{ {{0.4x+0.2y=3} \atop {0.7x-2.8y=-1.05}} \right. \\\\\\\left \{ {{0.4x=3-0.2y} \atop {0.7x-2.8y=-1.05}} \right. \\\\\\\left \{ {{x=2.5(3-0.2y)} \atop {0.7x-2.8y=-1.05}} \right. \\\\\\\left \{ {{x=7.5-0.5y} \atop {0.7x-2.8y=-1.05}} \right. \\\\\\\left \{ {{x=7.5-0.5y} \atop {0.7\cdot(7.5-0.5y)-2.8y=-1.05}} \right. \\\\\\\left \{ {{x=7.5-0.5y} \atop {5.25-0.35y-2.8y=-1.05}} \right.$

$\left \{ {{x=7.5-0.5y} \atop {5.25-0.35y-2.8y=-1.05}} \right. \\\\\\\left \{ {{x=7.5-0.5y} \atop {5.25-3.15y=-1.05}} \right. \\\\\\\left \{ {{x=7.5-0.5y} \atop {-3.15y=-6.3}} \right. \\\\\\\left \{ {{x=7.5-0.5y} \atop {y=2}} \right.\\\\\\\left \{ {{x=7.5-1} \atop {y=2}} \right.\\\\\\\left \{ {{x=6.5} \atop {y=2}} \right.$