1）5x/25x²=1/5x2)9ab²+6abc/3a²b=3ab(3b+2c)/3a²b=(3b+2x)/a3）9a²+6ab+b²/3a+b=(3a+b)²/(3a+b)=3a+b4)x²-36/2x+12=(x+6)(x-6)/2(x+6)=(x-6)/2