Question

用待定系数法确定（-x+1)/(x+1)(x+2)=A/(X+1)+B/(X+2)中A,B的值

用待定系数法确定（-x+1)/(x+1)(x+2)=A/(X+1)+B/(X+2)中A,B的值
初一的

Answer 1

(-x+1)/(x+1)(x+2)=A/(x+1)+B/(x+2)
对等式右边逗誉好通分得：(-x+1)/(x+1)(x+2)=[A(x+2)+B(x+1)]/[(x+1)(x+2)]
即(-x+1)/(x+1)(x+2)=[(A+B)x+(2A+B)]/[(x+1)(x+2)]
得：山铅
A+B=-1
2A+B=1
解虚山得A=2，B=-3

Answer 2

去分母得喊丛 -x+1=A(x+2)+B(x+1)
取信渗散x=-1得2=A*1，所以滑氏A=2
取x=2得3=B*（-1），所以B=-3 追问我算出来是:A=2, B=-3