Question

2y (y -1)-(5x -3xy)÷x

1 已知1÷y－1÷x＝5,求(2x+4xy－2y)÷(x-3xy-y)的值
2、已知X1+X3=3,X1X2=1
（1） 求(1÷X1)+(1÷X2)=?
(2) 求(X2÷X1)+(X1÷X2)=?
(3) 求(X2+1)÷(X1+1)+(X1+1)÷(X2+1)=?
第一题打错了，应该是已知1÷x－1÷y＝5,求(2x+4xy－2y)÷(x-3xy-y)的值
第二题也错了，应该是已知X1+X2=3,X1X2=1

Answer 1

计算：2y（y-1)-（5x-3xy)除以x

Answer 2

(2x+4xy－2y)÷(x-3xy-y)
=((2/y－2/x+4)*xy)÷((1/y-1/x-3)*xy)
=9/2
=4.5
(1÷X1)+(1÷X2)
=(x2+x1)/X1X2
=3
(X2÷X1)+(X1÷X2)
=(x2^2+x1^2)/x1x2
=(x1+x2)^2-2x1x2
=9-2
=7
(X2+1)÷(X1+1)+(X1+1)÷(X2+1)
=(X2+1)÷(X1+X1X2)+(X1+1)÷(X2+X1X2)
=(X2+1)÷(1+X2)÷X1+(X1+1)÷X2÷(X1+1)
=1/X1+1/X2
=3