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21^7/9^2*49^3

21 ^ 7 = ( 7 * 3) ^ 7 = 7 ^ 3 * 3 ^ 3 ---------------------------------------9^2 = 3 ^ 4 ---------------------------------------49 ^ 3 = 7 ^ 6 -------------------------------------( 7 ^ 3  * 3 ^ 3 ) / ( 3 ^ 4 * 7 ^ 6) = 1 / ( 3 * 7^3) = 1 / ( 3 * 343) = 1 / 1029 

21^7/9^2*49^3=(3*7)/3²·(7²)³=((3^7·7^7)/3^4)·7^6=3^3·7^13=27·7^13