Răspuns :
Răspuns:
a = (3²¹+3^20 +3^19):39
a = (9+3+1)•3^19:39
a = 13•3^19:39
a = 3^19/3
a = 3^18
a = (3^9)² → patrat perfect
==EVERGREEN==
Răspuns:
Explicație pas cu pas:
[tex]\bf a= \big(3^{21}+3^{20}+3^{19} \big): 39[/tex]
[tex]\bf a= 3^{19} \cdot \big(3^{21 - 19}+3^{20 - 19}+3^{19 -19 } \big): 39[/tex]
[tex]\bf a= 3^{19} \cdot \big(3^{2}+3^{1}+3^{0} \big): 39[/tex]
[tex]\bf a= 3^{19} \cdot \big(9+3+1 \big): 39[/tex]
[tex]\bf a= 3^{19} \cdot 13: 39[/tex]
[tex]\bf a= 3^{18} \cdot 3 \cdot \: 13: 39[/tex]
[tex]\bf a= 3^{18} \cdot 39: 39[/tex]
[tex]\bf a= 3^{18} \cdot 1[/tex]
[tex]\bf a= 3^{18} = \red{\big( 3^{9} \big)^{2} \implies patrat \: perfect}[/tex]