1.8/(x²+2)+(x²+2-5)/8=1
8/(x²+2)+(x²+2)/8-5/8-1=0
设(x²+2)/8=y,则原方程变为1/y+y-13/8=0,即8y²-13y+8=0
∵△=13²-4×8×8=169-256