Obtenha o resultado de:?

a) (2,5x10*12)(4,0x10*9)
b) (3,6x10*-4)(5,5x10*-5)
c) (1,2x10*8)(8,2x10*-5
d) (4,0x10*15)/(8,0x10*10) 

OBS:os * significa q o numero esta sendo elevado
porfavor a conta

basta usar a seguinte propriedade: 

(ax10*c)(bx10*d)=axbx10*(c+d)

Assim:

a)
(2,5x10*12)(4,0x10*9)=2,5x4,0x10*(9+12...
(2,5x10*12)(4,0x10*9)=10x10*21
======================================...
(2,5x10*12)(4,0x10*9)=1,0x10*22
======================================...

b)
(3,6x10*-4)(5,5x10*-5)=3,6x5,5x10*(-4-...
(3,6x10*-4)(5,5x10*-5)=19,8x10*(-9)
======================================...
(3,6x10*-4)(5,5x10*-5)=1,98x10*(-8)
======================================...

c)
(1,2x10*8)(8,2x10*-5)=1,2x8,2x10*(8-5)
======================================...
(1,2x10*8)(8,2x10*-5)=9,84x10*(3)
======================================...