已知|a一b|十根号b一9=0,
a-b=0 b-9=0解得a=b=9计算a²十ab/b²·a²一ab/a²一b²的值
=a(a+b)/b² * a(a-b)/(a-b)(a+b)
=a²/b²
=9²/9²
=1