Question

3x+5/(x+2)(x+3)=A/(x+2)+B/(X+3),求AB的值

Answer 1

原题你少些了一个括号吧?否则结构不对称就不象数学题.

A/(x+2)+B/(x+3)

=[A(x+3)+B(x+2)]/(x+2)(x+3)

=[(A+B)x+(3A+2B)]/(x+2)(x+3)

=(3x+5)/(x+2)(x+3)

所以

A+B=3

3A+2B=5

然后呢 ,A=-1,B=4

难道不对?为啥不给最佳~