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

Toán Lớp 7: Tính tổng A=5 + 10 + 20 + 40 + – + 1280+2560

Toán Lớp 7: Tính tổng A=5 + 10 + 20 + 40 + …. + 1280+2560

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  1. Answer
    A = 5 + 10 + 20 + 40 + … + 1280 + 2560
    2A = 2 . (5 + 10 + 20 + 40 + … + 1280 + 2560)
    2A = 10 + 20 + 40 + 80 + … + 2560 + 5120
    2A – A = (10 + 20 + 40 + 80 + … + 2560 + 5120) – (5 + 10 + 20 + 40 + … + 1280 + 2560)
    A = 5120 – 5
    A = 5115

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

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