For all positive integers m, [m] = 3m when m is odd and [m]=1/2 when m is even. Which of the following is equivalent to [9] × [6] ?
A. [81]
B. [54]
C. [36]
D. [27]
E. [18]
Λύση (D):
[9] = 3×9=27 (εφόσον το 9 είναι περιττός αριθμός)
[6]= 6/2=3
Άρα [9] × [6] = 27× 3=81
Επομένως ψάχνουμε ποια από τις επιλογές θα μας δώσει αντίστοιχα 81.
[81]= 3×81=243
[54]= 54/2 =27
[36]= 36/2= 18
[27]= 27×3 =81
[18]= 18/2=9
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