已知整式x²y的值是2,则5x²y+5xy-7x-(4x²y+5xy-7x)的值是多少
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![已知整式x²y的值是2,则5x²y+5xy-7x-(4x²y+5xy-7x)的值是多少](/uploads/image/z/2545313-41-3.jpg?t=%E5%B7%B2%E7%9F%A5%E6%95%B4%E5%BC%8Fx%26%23178%3By%E7%9A%84%E5%80%BC%E6%98%AF2%2C%E5%88%995x%26%23178%3By%2B5xy-7x-%EF%BC%884x%26%23178%3By%2B5xy-7x%EF%BC%89%E7%9A%84%E5%80%BC%E6%98%AF%E5%A4%9A%E5%B0%91)
已知整式x²y的值是2,则5x²y+5xy-7x-(4x²y+5xy-7x)的值是多少
已知整式x²y的值是2,则5x²y+5xy-7x-(4x²y+5xy-7x)的值是多少
已知整式x²y的值是2,则5x²y+5xy-7x-(4x²y+5xy-7x)的值是多少
式子 5x²y+5xy-7x-(4x²y+5xy-7x)
去括号 得5x²y+5xy-7x-4x²y-5xy+7x
其中 5x²y和--4x²y抵消 剩一个x²y
-7x和7x相抵消
5xy和-5xy相抵消
最后只剩一个x²y
由于x²y=2
所以结果是2
已知整式x²y的值是2,则5x²y+5xy-7x-(4x²y+5xy-7x)的值是多少
代入x²y=2
5x²y+5xy-7x-(4x²y+5xy-7x)
=10+5xy-7x-(8+5xy-7x)
=10+5xy-7x-8-5xy+7x
=2