b, (x+2)4+x4=82⇔(x+2)4−1+x4−81=0
⇔((x+2)2−1)((x+2)2+1)+(x2−9)(x2+9)=0
⇔(x+2+1)(x+2−1)(x2+4x+5)+(x−3)(x+3)(x2+9)=0
⇔(x+3)[(x+1)(x2+4x+5)+(x−3)(x2+9)]=0
⇔(x+3)(x3+4x2+5x+x2+4x+5+x3+9x−3x2−27)=0
⇔(x+3)[(2x3−2x2)+(4x2−4x)+(22x−22)]=0
⇔(x+3)(x−1)(2x2+4x+22)=0
⇔x= hoac x=−3