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

Toán Lớp 6: S= 2+2^3+2^5+…+2^99 có chia hết cho 10 không? Vì sao?

Toán Lớp 6: S= 2+2^3+2^5+…+2^99
có chia hết cho 10 không? Vì sao?

Comments ( 1 )

  1. Giải đáp:
     
    S= 2+$2^{3}$+ $2^{5}$+….+$2^{99}$
    S= (2+$2^{3}$+$2^{5}$+$2^{7}$)+($2^{9}$+$2^{11}$+$2^{13}$+$2^{15}$)+….+($2^{93}$+$2^{95}$+$2^{97}$+$2^{99}$)
    S=2(1+$2^{2}$+$2^{4}$+$2^{6}$)+$2^{9}$(1+$2^{2}$+$2^{4}$+$2^{6}$)+…+$2^{93}$(1+$2^{2}$+$2^{4}$+$2^{6}$)
    S=2.170+$2^{9}$+170+…+$2^{93}$ .170
    S=170(2+$2^{9}$+…+$2^{93}$ chia hết cho 10 (Đpcm)

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