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Determinati valoarea lui a din egalitatea 8a(aa-52)=2aa a are bară deasupra lui.

Răspuns :

scrii numerele in baza 10:
(80+a)(10a+a-52)=200+10a+a
(80+a)(11a-52)=200+11a
880a-4160+11a²-52a=200+11a
11a²+828a-11a-4160-200=0
11a²+817a-4360=0
Δ=b²-4ac=817²-4×11×(-4360)=667489+191840=859329
Δ>0
a1=(-b+√Δ)/2a=(-817+√859329)/2×11=(-817+927)/22=110/22=5
a2=(-b-√Δ)/2a=(-817-√859329)/2×11=(-817-927)/22=1744/22=79,(27)
deci a=5 
verificare 
85×(55-52)=255
85×3=255
255=255