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

Toán Lớp 7: help Tính nhanh các tích sau a , ( – 4 ) x 2 x 6 x 25 x ( -7 ) x 5 b , ( – 32 ) x 125 x ( – 9 ) x ( – 25 ) c , 47 x 69 – 31 x ( – 47 )

Toán Lớp 7: help
Tính nhanh các tích sau
a , ( – 4 ) x 2 x 6 x 25 x ( -7 ) x 5
b , ( – 32 ) x 125 x ( – 9 ) x ( – 25 )
c , 47 x 69 – 31 x ( – 47 )
d , ( – 56 ) + 8 x ( 11 + 7 )

Comments ( 1 )

  1. Tính nhanh
    a, (-4) xx 2 xx 6 xx 25 xx (-7) xx 5
      = [ (-4) xx 25) xx (2 xx 5) xx [ 6 xx (-7)]
    = (-100) xx 10 xx (-42)
    = (-1000) xx (-42)
    = 42000
    b, (-32) xx 125 xx (-9) xx 25
    = (-8) xx 4 xx 125 xx (-9) xx 25
    = [ (-8) xx 125] xx (4 xx 25) xx (-9)
    = (-1000) xx 100 xx (-9)
    = (-100000) xx (-9)
    = 900000
    c, 47 xx 69 – 31 xx (-47)
    = 47 xx 69 + 31 xx 47
    = 47 xx (69 + 31)
    = 47 xx 100
    = 4700
    d,(-56) + 8 xx (11 + 7)
    = 8 xx (-7) + 8 xx (11 + 7)
    = 8 xx (11 + 7 – 7)
    = 8 xx 11 = 88
     

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

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