Aratati ca urmatoarele numere sunt Cuburi perfecte :
a) x=64*56+64*8 b) y=8*7+8*5-8*4 c) z=27*95-27*68 d) t=27*26+27 e) u=27*28-27 f) 2 la puterea 61 - 2 la puterea 60 g) 3 la puterea 37 2*3 la puterea 36 h) s=3 la puterea 19 -3 la puterea 18- 3 la puterea 18
a) x=64·(56+8)=64·64=4³·4³=(4·4)³=16³ b) y=8·(7+5-4)=8·8=2³·2³=(2·2)³=4³ c) z=27·(95-68)=27·27=3³·3³=(3·3)³=9³ d) 27·(26+1)=27·27=3³·3³=(3·3)³=9³ e) 27·(28-1)=27·27=...=9³ (vezi analog la c) si d)) f) 2⁶¹-2⁶⁰=2⁶⁰·(2¹-1)=2⁶⁰=(2²⁰)³ g) 3³⁷-2·3³⁶=3³⁶·(3¹-2)=3³⁶=(3¹²)³ h) s=3¹⁹-3¹⁸-3¹⁸=3¹⁸·(3-1-1)=3¹⁸=(3⁶)³=729³