Răspuns:
[tex]\bf a)~~3^{69} = 3^{23\cdot 3} =\red{\Big(3^{23}\Big)^{3}}\rightarrow cub ~perfect[/tex]
[tex]\bf b)~~4^{51} =4^{17\cdot 3} =\blue{\Big(4^{17}\Big)^{3}}\rightarrow cub ~perfect[/tex]
[tex]\bf c)~~8^{61} =\Big(2^{3}\Big)^{61} =2^{61\cdot 3} =\purple{\Big(2^{61}\Big)^{3}}\rightarrow cub ~perfect[/tex]
[tex]\bf d)~~5^{21} = 5^{7\cdot 3} =\green{\Big(5^{7}\Big)^{3}}\rightarrow cub ~perfect[/tex]
[tex]\bf e)~~19^{33} = 19^{11\cdot 3} =\purple{\Big(19^{11}\Big)^{3}}\rightarrow cub ~perfect[/tex]
[tex]\bf f)~~17^{42} = 17^{14\cdot 3} =\red{\Big(17^{14}\Big)^{3}}\rightarrow cub ~perfect[/tex]
[tex]\bf g)~~27^{28} =\Big(3^{3}\Big)^{28} =3^{28\cdot 3} =\pink{\Big(3^{28}\Big)^{3}}\rightarrow cub ~perfect[/tex]
