解(1)原式=5x/(25x²) 分子、分母约去5x=1/(5x)解(2)原式=(9ab²+6abc)/(3a²b)=3ab(3b+2c)/(3a²b) 分子、分母约去3ab=(3b+2c)/a解(3)原式=(9a²+6ab+b²)/(3a+b)=(3a+b)&...