Question

25 баллов!!!решить систему уравнений : 2x+3y/4+3x-2y/5=-1/20
3x+4y/2-5x-y/3=43/6

Answer 1

$begin{cases}frac{2x + 3y}{4} +frac{3x-2y}{5}=-frac{1}{20} /*20 \frac{3x + 4y}{2}-frac{ 5x-y}{3} = frac{43}{6} /*6end{cases}\\begin{cases} 5(2x + 3y)+ 4(3x-2y) =-1\ 3(3x + 4y)-2(5x-y )=43end{cases}\\begin{cases} 10x + 15y + 12x-8y =-1\ 9x + 12y -10x+2y=43end{cases} \\begin{cases} 22x + 7y =-1 /*(-2)\ -x+14y =43 end{cases} \\begin{cases} -44x -14y =2\ - x+14y =43 end{cases}\+--------\ -45x=45 /:(-45)$

$x=-1\\22x+7y=-1\22*(-1)+7y=-1\-22+7y=-1\7y=-1+22\7y=21 /:7\y=3\\begin{cases} x=-1 \ y=3 end{cases}$