Question

жпжпжжп решите дам 40 баллов ​

Answer 1

Пошаговое объяснение:

$1)\left \{ {{3x-y=11} \atop {x+2y=27}} \right. =\left \{ {{6x-2y=22} \atop {x+2y=27}} \right.\\\\ 5x=-5\\x=-5:5\\x=-1\\\\x+2y=27\\-1+2y=27\\2y=27+1\\2y=28\\y=28:2\\y=14$

$2)\left \{ {{4x+y=10} \atop {y-x=-5}} \right.=\left \{ {{4x+y=10} \atop {-x+y=-5}} \right.=\left \{ {{4x+y=10} \atop {-4x+4y=-20}} \right.\\\\ -3y=-10\\y=-10:(-3)\\y=\frac{10}{3}\\\\ 4x+y=10\\\\4x+\frac{10}{3}=10\\\\ 4x=10-\frac{10}{3} \\\\4x=\frac{30}{3}-\frac{10}{3}\\\\ 4x=\frac{20}{3} \\\\x=\frac{20}{3}:4\\\\ x=\frac{20}{3}*\frac{1}{4}\\\\ x=\frac{5}{3}$

$3)\left \{ {{4x-y=19} \atop {x+15y=20}} \right.=\left \{ {{60x-15y=285} \atop {x+15y=20}}\right. \\\\ 59x=265\\x=\frac{265}{59}\\\\ x+15y=20\\\\\frac{265}{59}+15y=20\\\\ 15y=20-\frac{265}{59}\\\\ 15y=\frac{1180}{59}-\frac{265}{59}\\\\ 15y=\frac{915}{59}\\\\ y=\frac{915}{59}:15\\\\ y=\frac{915}{59} *\frac{1}{15}\\\\ y=\frac{61}{59}$