Question

已知x的平方减9除以6x=x+3除A+x-3除B,则A=多少,B等于多少

Answer 1

左边=6x/(x^2-9)=6x/[(x+3)(x-3)]

右边=A/(x+3)+B/(x-3)=[A(x-3)+B(x+3)]/[(x+3)(x-3)]

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

故A+B=6, A-B=0

解A=B=3