a) 9² = 9 • 9 = 81
b) 7-² = 1/7 • 1/7 = 1/49
c) (-17)² = -17 • (-17) = 289
d) (-2,8)² = -2,8 • (-2,8) = 7,84
e) (5/6)-³ = 6/5 • 6/5 • 6/5 = 216/125
