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

Toán Lớp 6: Bài 1:Tính nhanh nếu có a) 75+58×50-58×25 b)20:2×2-5x5x5:5×5 c)29-[16+3x(51-49)] d)500-{5x[409-(8×3-21)x4]+1000}:15 e)1+2+3+…+99 f)10

Toán Lớp 6: Bài 1:Tính nhanh nếu có
a) 75+58×50-58×25
b)20:2×2-5x5x5:5×5
c)29-[16+3x(51-49)]
d)500-{5x[409-(8×3-21)x4]+1000}:15
e)1+2+3+…+99
f)10+12+14+…+2010
Bài 2: Tìm X:
a)7+2xX=9
b)8:x-1=3
c)1/3+2/3xX=6/7
d)4+X=8-X
e)X+2xX+3xX+4xX+..+9xX=90
Làm ơn giúp ,mk cần gấp

Comments ( 2 )

  1. Bài 1: 
    a) 75 + 58 x 50 – 58 x 25
    = 58 x (50 – 25) + 75
    = 58 x 25 + 75
    =
    b) 20 : 2 x 2 – 5 x 5 x 5 : 5 x 5
    = 20 – 125
    = – 105
    c) 29 – [16 + 3 x (51 – 49)]
    = 29 – [16 + 3 x 2]
    = 29 – [16 + 6]
    = 29 – 22
    = 7
    d) 500 – {5 x [409 – (8 x 3 – 21) x 4] +1000} : 15
    = 500 – {5 x [409 – 3 x 4] + 1000} : 15
    = 500 – {5 x 385 + 1000} : 15
    = 500 – 2925 : 15
    = 500 – 195
    = 305
    Bài 2: 
    a) 7 + 2 x X = 9
              2 x X = 9 – 7
              2 x X = 2
                    X = 2 : 2
                    X = 1
    b) 8 : X – 1 = 3
        8 : X       = 3 + 1
        8 : X       = 4
             X       = 8 : 4
             X       = 2
    c) 1/3 + 2/3 x X = 6/7
                  2/3 x X = 6/7 – 1/3
                  2/3 x X = 11/21
                           X = 11/21 : 2/3
                           X = 11/14
     

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