a²(x-y)-b²(x-y),=(x-y)(a²-b²)=(x-y)(a-b)(a+b)1.25的4次方分之0.5的4次方×0.4的4次方×12.4的4次方=0.5^4×0.4^4×12.4^4/1.25^4=(0.5×0.4×12.4/1.25)^4=(2.48/1.25)^4=1.984^4【这个题目...