Question

急求(x^2-3x-1)/(x-1)-(x^2+3x+3)/(x+3)+(2x+12)/(x+3) 如何用裂项法来计算这

Answer 1

首先我想问下式子后两项分母都是X+3为什么分开写?

1)x^2-3x-1=x^2-x-2x+2-3=x(x-1)-2(x-1)-3

2)-(x^2+3x+3)+2x+12=-x^2-x+9=-[x^2+3x-2x-6-3]=-[x(x+3)-2(x+3)-3]

前面2式分别除仪去分母,化简得x-2-3/x-1-x+2+3/x+3=3/x+3-3/x-1