Методом сложения
3X + X^2 + Y - Y = 10 + 8
X^2 + 3X - 18 = 0
D = 9 + 72 = 81 ; √ D = 9
X1 = ( - 3 + 9 ) : 2 = 3
X2 = ( - 3 - 9 ) : 2 = - 6
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3X + Y = 10
Y = 10 - 3X
Y1 = 10 - 3 * 3 = 1
Y2 = 10 - 3 * ( - 6 ) = 10 + 18 = 28
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ОТВЕТ ( 3 ; 1 ) ; ( - 6 ; 28 )