Bonsoir,
8² = 8*8 = 64
(-5)³ = -5*-5*-5 = -125
2^-4 = 1/ 2^4 = 1/ (2*2*2*2) = 1/16 =0,0625
5^-2= 1/(5*5) = 1/25 =0,04
