数学的分式问题

来源:百度知道 编辑:UC知道 时间:2024/04/29 23:17:13
已知(2x-3)/(x+2)(x-3)=A/(x+2)-B/(x-3),求A,B

(2x-3)/(x+2)(x-3)=A/(x+2)-B/(x-3)
(2x-3)/(x+2)(x-3)=[A*(x-3)-B*(X+2)]/(x+2)(x-3)
(2x-3)/(x+2)(x-3)=[Ax-3A-Bx-2B]/(x+2)(x-3)
(2x-3)/(x+2)(x-3)=[(A-B)x-(3A+2B)]/(x+2)(x-3)
A-B=2
3A+2B=3
A=7/5
B=-3/5

A=7/5 B=-3/5
过程:
(X-3)*A-(X+2)*B = 2X-3

A-B=2
3A+2B=3
联立即可解得。

A=7/5 B=-3/5
过程:
(X-3)*A-(X+2)*B = 2X-3

A-B=2
3A+2B=3
或:
(2x-3)/(x+2)(x-3)=A/(x+2)-B/(x-3)
(2x-3)/(x+2)(x-3)=[A*(x-3)-B*(X+2)]/(x+2)(x-3)
(2x-3)/(x+2)(x-3)=[Ax-3A-Bx-2B]/(x+2)(x-3)
(2x-3)/(x+2)(x-3)=[(A-B)x-(3A+2B)]/(x+2)(x-3)
A-B=2
3A+2B=3
A=7/5
B=-3/5

等号右边A(X-3)+B(X+2)/(X+2)(X-3)
所以:2X-3=A(X-3)+B(X+2)=(A+B)X-3A+2B
所以:A+B=2;-3A+2B=-3
计算得出A=7/5;B=3/5
如果非要在写成第一个分式减去第二个分式(就像你题目中等号右边那样),那么B=-3/5