Tìm n, biết

Giải SBT Toán 6 Bài 6: Lũy thừa với số mũ tự nhiên

Bài 1.56

Tìm n, biết:

a) $5^4=n$;                                     

b) $n^3=125$;                                

c) ${11}^n=1331$

Lời giải.

a) $5^4=n$;                                                                   

      Hay $n=5^4$= 5. 5. 5. 5 = 25. 5. 5 = 125. 5 = 625                                                                                                    

Vậy n = 625.                                        

b) $n^3=125n^3=\mathrm{5.5.5}{n}^3=5^3$;                           

   n = 5                                          

Vậy n = 5.                                        

c) ${11}^n=1331{11}^n=\mathrm{11.11.11}{11}^n={11}^3$   

 Vậy n = 11.