2x²-3xy-5y²=0,求(x-y)除以(2x+y)的值,求出x/y=﹣1或x/y=5/2后怎么做?
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![2x²-3xy-5y²=0,求(x-y)除以(2x+y)的值,求出x/y=﹣1或x/y=5/2后怎么做?](/uploads/image/z/5241852-36-2.jpg?t=2x%26%23178%3B-3xy-5y%26%23178%3B%3D0%2C%E6%B1%82%28x-y%29%E9%99%A4%E4%BB%A5%282x%2By%29%E7%9A%84%E5%80%BC%2C%E6%B1%82%E5%87%BAx%EF%BC%8Fy%3D%EF%B9%A31%E6%88%96x%EF%BC%8Fy%3D5%2F2%E5%90%8E%E6%80%8E%E4%B9%88%E5%81%9A%3F)
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2x²-3xy-5y²=0,求(x-y)除以(2x+y)的值,求出x/y=﹣1或x/y=5/2后怎么做?
2x²-3xy-5y²=0,求(x-y)除以(2x+y)的值,求出x/y=﹣1或x/y=5/2后怎么做?
2x²-3xy-5y²=0,求(x-y)除以(2x+y)的值,求出x/y=﹣1或x/y=5/2后怎么做?
2x²-3xy-5y²=0
首先用十字相乘法因式分解,有:
2 -5
1 1
得:(2x-5y)(x+y)=0
有:2x-5y=0……………………(1)
或:x+y=0………………………(2)
由(2)有:x=-y……………………(3)
代(3)入(1),有:-2y-5y=0
解得:y=0
代入(3),得:x=0
而题目要求(x-y)/(2x+y),分母2x+y=2×0+0=0
因此,所求之式无意义.