(2) 2 (b) 3-(-2b) 3(-)=______________.
-52×(-5) 2×5-4=_____________.
0.258×643×258×48=______________.
已知Axn+1=x2n+1,则A=_____________.
已知10a=5,10b=25,则 =____________.
3__________m+1=2m+4