(1)48a-48b=48(a-b)=48×(178-53)=48×125=6000(2)a²-1.3b=2.6²-1.3×1.3=2.6²-1.3²=(2.6+1.3)(2.6-1.3)=3.9×1.3=5.07
48a-48b=48×（a-b）=48×（178-53）=48×125=6000
