解1题因为a-1/a=3(a-1/a)²=3²a²+1/a²-2×a×1/a=9a²+1/a²-2=9a²+1/a²=11解2题：(x+y+z)(x-y-z)=[x+(y+z)][x-(y+z)],用平方差公式=x²-(y+z)²=x²-(y²+2yz+z²)=x²-y²-z²-2yz
