Răspunsuri

2014-09-21T11:01:56+03:00
7^(11+12+.+30)=7^3n.7²=7^(3n+2)
11+12+............+30=(11+30).20/2=410
7^410=7^(3n+2)
ca sa fie egale trebuie ca
3n+2=410
3n=410-2=408
n=408:3=136
n=136