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se stie ca 3 la puterea x +3 la puterea x+1=108

Răspuns :

3^x+3^(x+1)=108
3^x+3^x*3^1=108
Notam 3^x=t
=> t+t*3=108
t+3t=108
4t=108
t=108:4
t=27=3*3*3=3^3
t=3^x
=> x=3

VERIFICARE:
3^3+3^(3+1)=108
27+3^4=108
27+81=108
108=108