a²-ab/a-b
=a(a-b)/(a-b)
=a
2a²(x－y)³/a(y－x)
=-2a(x-y)²
a²＋ab/a²＋2ab＋b²
=a(a+b)/(a+b)²
=a/(a+b)
x²－x－2/4－x²
=(x-2)(x+1)/(2-x)(2+x)
=-(x+1)/(x+2)
a²＋4a＋3/a²＋a－6
=(a+3)(a+1)/(a+3)(a-2)
=(a+1)/(a-2)