解方程组：3x减2y等于1 2x加3y等于负7
2个回答
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3x - 2y = 1 (1)
2x + 3y = -7 (2)
(1) + (2)
==> 5x + y = -6
==> y = -5x - 6 (3)
(3)代入(1)
==> 3x - 2 * (-5x - 6) = 1
==> 3x + 10x + 12 = 1
==> 13x = -11
==> x = -11/13 (4)
(4)代入(3)
==> y = -5 * (-11/13) - 6
==> y = 55/13 - 6
==> y = - 23/13
2x + 3y = -7 (2)
(1) + (2)
==> 5x + y = -6
==> y = -5x - 6 (3)
(3)代入(1)
==> 3x - 2 * (-5x - 6) = 1
==> 3x + 10x + 12 = 1
==> 13x = -11
==> x = -11/13 (4)
(4)代入(3)
==> y = -5 * (-11/13) - 6
==> y = 55/13 - 6
==> y = - 23/13
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