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а) Решите методом алгебраического сложения систему уравнений:
![left { {{x+y=2} atop {x-y=3}} right. \ left { {{x=2-y} atop {x-y=3}} right. \ 2-y-y=3 \ -2y=3-2 \ -2y=1 \ y=- frac{1}{2}=-0,5 \ left { {{y-0,5} atop {x=2-(-0,5)=2+0,5=2,5}} right. \ left { {{y=-0,5} atop {x=2,5}} right. \ left { {{x+y=2} atop {x-y=3}} right. \ left { {{x=2-y} atop {x-y=3}} right. \ 2-y-y=3 \ -2y=3-2 \ -2y=1 \ y=- frac{1}{2}=-0,5 \ left { {{y-0,5} atop {x=2-(-0,5)=2+0,5=2,5}} right. \ left { {{y=-0,5} atop {x=2,5}} right. \](https://tex.z-dn.net/?f=+left+%7B+%7B%7Bx%2By%3D2%7D+atop+%7Bx-y%3D3%7D%7D+right.++%5C++left+%7B+%7B%7Bx%3D2-y%7D+atop+%7Bx-y%3D3%7D%7D+right.++%5C+2-y-y%3D3+%5C+-2y%3D3-2+%5C+-2y%3D1+%5C+y%3D-+frac%7B1%7D%7B2%7D%3D-0%2C5+%5C++left+%7B+%7B%7By-0%2C5%7D+atop+%7Bx%3D2-%28-0%2C5%29%3D2%2B0%2C5%3D2%2C5%7D%7D+right.+++%5C++left+%7B+%7B%7By%3D-0%2C5%7D+atop+%7Bx%3D2%2C5%7D%7D+right.++%5C+)
б)
![left { {{2x-3y=1} atop {y-4x=2}} right \ left { {{2x-3y=1} atop {y=2+4x}} right. \ 2x+3*(2+4x)=1 \ 2x-6-12x=1 \ -10x=1+6 \ -10x=7 \ x= -frac{7}{10} =-0,7 \ left { {{x=- frac{7}{10} } atop {y=2+4* (-frac{7}{10})}} right. \ y=- frac{16}{5}=-3 frac{1}{5} \ left { {{x=-0,7} atop {y= -3frac{1}{5} }} right. left { {{2x-3y=1} atop {y-4x=2}} right \ left { {{2x-3y=1} atop {y=2+4x}} right. \ 2x+3*(2+4x)=1 \ 2x-6-12x=1 \ -10x=1+6 \ -10x=7 \ x= -frac{7}{10} =-0,7 \ left { {{x=- frac{7}{10} } atop {y=2+4* (-frac{7}{10})}} right. \ y=- frac{16}{5}=-3 frac{1}{5} \ left { {{x=-0,7} atop {y= -3frac{1}{5} }} right.](https://tex.z-dn.net/?f=+left+%7B+%7B%7B2x-3y%3D1%7D+atop+%7By-4x%3D2%7D%7D+right+%5C+left+%7B+%7B%7B2x-3y%3D1%7D+atop+%7By%3D2%2B4x%7D%7D+right.+%5C+2x%2B3%2A%282%2B4x%29%3D1+%5C+2x-6-12x%3D1+%5C+-10x%3D1%2B6+%5C+-10x%3D7+%5C+x%3D+-frac%7B7%7D%7B10%7D+%3D-0%2C7+%5C+left+%7B+%7B%7Bx%3D-+frac%7B7%7D%7B10%7D+%7D+atop+%7By%3D2%2B4%2A+%28-frac%7B7%7D%7B10%7D%29%7D%7D+right.+%5C+y%3D-+frac%7B16%7D%7B5%7D%3D-3+frac%7B1%7D%7B5%7D+%5C+left+%7B+%7B%7Bx%3D-0%2C7%7D+atop+%7By%3D+-3frac%7B1%7D%7B5%7D+%7D%7D+right.+)
2) Решите систему уравнений:
![left { {{ frac{x}{y} = frac{2}{3} } atop {4x-5y=8}} right. \ left { {{3y=2x} atop {4x-5y=8}} right. \ left { {{y= frac{2x}{3} } atop {4x-5* frac{2x}{3}=8 }} right. \ 4x- frac{10}{3}x=8 \ 4x-3frac{1}{3} x=8 \ frac{2}{3}x=8 \ x=8* frac{3}{2}=12 \ left { {{x=12} atop {y= frac{2*12}{3}=8 }} right. \ left { {{x=12} atop {y=8}} right. left { {{ frac{x}{y} = frac{2}{3} } atop {4x-5y=8}} right. \ left { {{3y=2x} atop {4x-5y=8}} right. \ left { {{y= frac{2x}{3} } atop {4x-5* frac{2x}{3}=8 }} right. \ 4x- frac{10}{3}x=8 \ 4x-3frac{1}{3} x=8 \ frac{2}{3}x=8 \ x=8* frac{3}{2}=12 \ left { {{x=12} atop {y= frac{2*12}{3}=8 }} right. \ left { {{x=12} atop {y=8}} right.](https://tex.z-dn.net/?f=+left+%7B+%7B%7B+frac%7Bx%7D%7By%7D+%3D+frac%7B2%7D%7B3%7D+%7D+atop+%7B4x-5y%3D8%7D%7D+right.++%5C+++left+%7B+%7B%7B3y%3D2x%7D+atop+%7B4x-5y%3D8%7D%7D+right.++%5C++left+%7B+%7B%7By%3D+frac%7B2x%7D%7B3%7D+%7D+atop+%7B4x-5%2A+frac%7B2x%7D%7B3%7D%3D8+%7D%7D+right.+++%5C+4x-+frac%7B10%7D%7B3%7Dx%3D8+%5C+++4x-3frac%7B1%7D%7B3%7D+x%3D8+%5C++frac%7B2%7D%7B3%7Dx%3D8+%5C+x%3D8%2A+frac%7B3%7D%7B2%7D%3D12+%5C++left+%7B+%7B%7Bx%3D12%7D+atop+%7By%3D+frac%7B2%2A12%7D%7B3%7D%3D8+%7D%7D+right.++++%5C++left+%7B+%7B%7Bx%3D12%7D+atop+%7By%3D8%7D%7D+right.+)
б)
2) Решите систему уравнений:
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