已知方程组x+y=3 2x²+3y²=18的解为x=x1 y=y1 ,x=x2 y=y2,求x1y2+x2y1的值再帮我解个方程组!2x²-2xy+x+y-4=0 3x²-3xy+x-2=0
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![已知方程组x+y=3 2x²+3y²=18的解为x=x1 y=y1 ,x=x2 y=y2,求x1y2+x2y1的值再帮我解个方程组!2x²-2xy+x+y-4=0 3x²-3xy+x-2=0](/uploads/image/z/5496929-17-9.jpg?t=%E5%B7%B2%E7%9F%A5%E6%96%B9%E7%A8%8B%E7%BB%84x%2By%3D3+2x%26%23178%3B%2B3y%26%23178%3B%3D18%E7%9A%84%E8%A7%A3%E4%B8%BAx%3Dx1+y%3Dy1+%2Cx%3Dx2+y%3Dy2%2C%E6%B1%82x1y2%2Bx2y1%E7%9A%84%E5%80%BC%E5%86%8D%E5%B8%AE%E6%88%91%E8%A7%A3%E4%B8%AA%E6%96%B9%E7%A8%8B%E7%BB%84%212x%26%23178%3B-2xy%2Bx%2By-4%3D0+3x%26%23178%3B-3xy%2Bx-2%3D0)
已知方程组x+y=3 2x²+3y²=18的解为x=x1 y=y1 ,x=x2 y=y2,求x1y2+x2y1的值再帮我解个方程组!2x²-2xy+x+y-4=0 3x²-3xy+x-2=0
已知方程组x+y=3 2x²+3y²=18的解为x=x1 y=y1 ,x=x2 y=y2,求x1y2+x2y1的值
再帮我解个方程组!2x²-2xy+x+y-4=0 3x²-3xy+x-2=0
已知方程组x+y=3 2x²+3y²=18的解为x=x1 y=y1 ,x=x2 y=y2,求x1y2+x2y1的值再帮我解个方程组!2x²-2xy+x+y-4=0 3x²-3xy+x-2=0
将y=3-x代入2x²+3y²=18得
5x²-18x+9=0
x=3或3/5
所以y=0或12/5
所以x1y2+x2y1=36/5
第二题
一式乘以三减去二式乘以二得
y=(8-x)/3
再将y值代入二式
得4x²-7x-2=0
解得x=2或-1/4
回代就可以解得
y=2或-1/2
x+y=3 2x²+3y²=18 5x²-18x+9=0 (x-3)(5x-3)=0
x1=3 y1=0
x2=3/5 y2=12/5
x1y2+x2y1=36/5再帮我解个方程组! 2x²-2xy+x+y-4=0 3x²-3xy+x-2=0 谢谢2x²-2xy+x+y...
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x+y=3 2x²+3y²=18 5x²-18x+9=0 (x-3)(5x-3)=0
x1=3 y1=0
x2=3/5 y2=12/5
x1y2+x2y1=36/5
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