解方程组x²+5xy-2x=3y+1=0;3x²+15xy-7x+8y+4=0
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解方程组x²+5xy-2x=3y+1=0;3x²+15xy-7x+8y+4=0
解方程组x²+5xy-2x=3y+1=0;3x²+15xy-7x+8y+4=0
解方程组x²+5xy-2x=3y+1=0;3x²+15xy-7x+8y+4=0
x²+5xy-2x+3y+1=0 (1)
(1)×3-(2)得
x+y-1=0
x=1-y (3)
把(3)代入(1)得
1-2y+y²+5y-5y²-2+2y+3y+1=0
-4y²+8y=0
y=0 y=2
把y=0,y=2代入(3)得
x=1或x=-1
∴x=1 x=-1
y=0 y=2
∵x²+5xy-2x=3y+1=0
∴3x²+15xy-6x=0
∴把3x²+15xy-6x=0代入第二个式子得
8y-x+4=0
∵3y+1=0
∴y=-1/3
∴-8/3-x+4=0
∴x=-4/3