a)4(32+1)(34+1)(38+1)
=21.(32−1)(32+1)(34+1)(38+1)
=21.(34−1)(34+1)(38+1)
=21.(38−1)(38+1)
=21.(316−1)
=21316−21
b) 48(52+1)(54+1)−.(532+1)
=2.(52−1)(52+1)(54+1)−.(532+1)
=2.(54−1)(54+1)−.(532+1)
=2.(58+1)−.(532+1)
=2.(532−1)
=2.532−2
Tham khảo nhé~