Question

Решите систему уравнений: х²+ху=9+3у 3х+2у=-1

Answer 1

X2 + xy = 9 + 3y;
3x + 2y = -1;
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x2 + x(-(1 + 3x)/2)= 9 - 3 * ((1 + 3x)/2);
y = - (1 + 3x)/ 2;
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x2 - (x - 3x2)/2 = 9 - (3 - 9x)/2; | *2;
2x2 - x - 3x2 = 18 - 3 -9x;
x2 + 8x - 15 = 0;
D = 64 - 60 = 4;
x1 = (8 + 2)/ 2 = 5;
x2 = (8 - 2)/2 = 3;
y1 = (-1 -  3*5)/2 = - 8;
y2 = (- 1 - 9)/2 = -5;