1/(x*x-2x-3)+2/(x*-x-6)+3/(x*x+3x+2)=0

1/(x*x-2x-3)+2/(x*-x-6)+3/(x*x+3x+2)=0


1/(x*x-2x-3)+2/(x*x-x-6)+3/(x*x+3x+2)=1/(x-3)*(x+1)+2/(x-3)*(x+2)+3/(x+1)*(x+2)=[(x+2)+2(x+1)+3(x-3)]/(x+1)(x+2)(x-3)=(6x-5)/(x+1)(x+2)(x-3),因為分母不能為零所以6x-5=0 x=5/6



0.4x加上0.3x等於18.9,求x


0.4x+0.3x=18.9 ==》0.7x=18.9 ==》x=18.9/0.7=27