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2014-11-09T22:13:04+02:00
9^x·9²+9^x·9+9^x=91·(3²)¹⁴
3^2x·81+3^2x·9+3^2x=91·(3²)¹⁴
3^2x(81+9+1)=91·(3²)¹⁴
3^2x·91=91·(3²)¹⁴
notam 91·3²=t
t^x=t^14
x=14