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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: chứng minh rằng 17^5+24^4 -13^21 chia hết cho 10

Toán Lớp 6: chứng minh rằng 17^5+24^4 -13^21 chia hết cho 10

Comments ( 2 )

  1. Ta có :
    17^5 = 17^4 . 17 = \overline{…1} . 17 = \overline{…7}
    24^4 = \overline{…6}
    13^21 = 13^20 . 13 = \overline{…1} . 13 = \overline{…3}
    Vậy :
    17^5 + 24^4 – 13^21
    = \overline{…7} + \overline{…6} – \overline{…3}
    = \overline{…3} – \overline{…3}
    = \overline{…0} \vdots 10
    Vậy 17^5 + 24^4 – 13^21 \vdots 10
    #dtkc

  2. Trả lời:
    $\text{Ta có:}$
    17^5=17^4 .17=(…1).17=(…7)
    24^4=(…6)
    13^21=13^20 .13=(…1).13=(…3)
    <=>17^5+24^4-13^21=(…7)+(…6)-(…3)=(…0)
    $\text{Vì các số có chữ số tận cùng là 0 luôn chia hết cho 10}$
    =>17^5+24^4-13^21=(…7)+(…6)-(…3)=(…0) \vdots 10
    =>17^5+24^4-13^21 \vdots 10

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222-9+11+12:2*14+14 = ? ( )