5/x+3+6/x的平方-9=1/x-3
1个回答

你写的有问题,估计是这样的：

第1题

5/(x+3)+6/(x^2-9)=1/(x-3)

5/(x+3)+6/((x+3)(x-3))=1/(x-3) 两边都乘以(x+3)(x-3)得

5(x-3)+6=x+3

x=3

第2题

(5x-4)/(2x-4)=(3x+5)/(3x-6)-2

(5x-4)/(2(x-2)=(3x+5)/(3(x-2)-2两边都乘以6(x-2)得

3(5x-4)=2(3x-5)-6*2(x-2)

x=46/21

第3题猜不出来是什么

第4题

(3-x)/(1-x)-(5-x)/(7-x)=1-(x^2-1)/((x-1)(x-7))

(x-3)/(x-1)-(x-5)/(x-7)=1-(x^2-1)/((x-1)(x-7))两边都乘以(x-1)(x-7)得

(x-3)(x-7)-(x-5)(x-1)=(x-1)(x-7)-(x^2-1)

(x^2-10x+21)-(x^2-6x+5)=(x^2-8x+7)-(x^2-1)

x=-2

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