【分式的加减】计算题(1)(x+y / x-y)+(2x / y-x)=(2)(2x / x ² -y ² )+(3x / y ² -x ² )+【x / (x+y)(y-x)】=(3)(x ² -x-2 / x+3)÷(2-x)+(x+1 / x+3)=

问题描述:

【分式的加减】计算题
(1)(x+y / x-y)+(2x / y-x)=
(2)(2x / x ² -y ² )+(3x / y ² -x ² )+【x / (x+y)(y-x)】=
(3)(x ² -x-2 / x+3)÷(2-x)+(x+1 / x+3)=

1)(x+y / x-y)+(2x / y-x)
=(x+y)/(x-y)-2x/(x-y)
=(x+y-2x)/(x-y)
=(y-x)/(x-y)
=-1
(2)(2x / x ² -y ² )+(3x / y ² -x ² )+【x / (x+y)(y-x)】
=2x/(x²-y²)-3x/(x²-y²)-x/(x²-y²)
=(2x-3x-x)/(x²-y²)
=-2x/(x²-y²)
(3)(x ² -x-2 / x+3)÷(2-x)+(x+1 / x+3)
=(x²-x-2)/(x+3)(2-x)+(x+1)/(x+3)
=(x²-x-2)/(x+3)(2-x)+(x+1)(2-x)/(x+3)(2-x)
=(x²-x-2+2x+2-x²-x)/(x+3)(2-x)
=0/(x+3)(2-x)
=0