Bonsoir,
Exercice 16:
8^2 =8x8=64
(-5)^3= (-5)x(-5)x(-5)=-125
2^-4=1/2^4 =1/16
5^-2=1/5^2=1/25
Exercice 19:
1)= -23
2)= 27
3)=-20
4)=100
5)=-100
Exercice 22:
1) 1x 10^3
2)0,01
3)10000
4)1x10^5
Exercice 25:
1)154000
2)0,007
3)6,2x10^-4
4)1,8x10^11
Voilà, bonne soirée