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

Toán Lớp 7: bài 1. a. (409/13 + 214/41) – 474/13 b. 0,25 + 3/5 – ( 1/8 – 2/5 + 5/4) c. (8 – 9/4 + 2/7 ) – ( -6 – 3/7 + 5/4 ) – ( 3 + 2/4 – 9/7) d.

Tháng Chín 19, 2022 Toán học 1 Comment 0 views

Toán Lớp 7: bài 1.
a. (409/13 + 214/41) – 474/13
b. 0,25 + 3/5 – ( 1/8 – 2/5 + 5/4)
c. (8 – 9/4 + 2/7 ) – ( -6 – 3/7 + 5/4 ) – ( 3 + 2/4 – 9/7)
d. 1/3 – 3/5 + 5/7 – 7/9 + 9/11 – 11/13 +13/15 + 11/13 – 9/11 + 7/9 – 5/7 + 3/5 – 1/3
e. 1/2014 – 1/2014.2013 – 1/2013.2012 -….- 1/3.2 – 1/2.1
tìm x:
-4/7 – x = 3/5 – 2x
mn giúp e vs nha:((

Comments ( 1 )

  1. maianhnhiquynh
    maianhnhiquynh
    19 Tháng Chín, 2022 at 5:11 sáng
    Reply
    Giải đáp:
    Bài 1:
    a/ (409/13 + 214/41) – 474/13
    = 409/13 + 214/41 – 474/13
    = (409/13 – 474/13)+ 214/41
    = -5+ 214/41
    = (-205)/41+214/41
    = 9/41
    b/ 0,25 + 3/5 – ( 1/8 – 2/5 + 5/4)
    = 1/5+3/5-1/8+2/5-5/4
    = (1/5+3/5+2/5)-(1/8+5/4)
    = 6/5-11/8
    = -7/40
    c/ (8 – 9/4 + 2/7 ) – ( -6 – 3/7 + 5/4 ) – ( 3 + 2/4 – 9/7)
    = 8 – 9/4 + 2/7+6 + 3/7 – 5/4 -3- 2/4 + 9/7
    = (8+6-3)+(-9/4-5/4-2/4)+(2/7+3/7+9/7)
    = 11-4+2
    = 9
    d/ 1/3 – 3/5 + 5/7 – 7/9 + 9/11 – 11/13 +13/15 + 11/13 – 9/11 + 7/9 – 5/7 + 3/5 – 1/3
    = (1/3- 1/3)+(- 3/5+ 3/5)+(5/7- 5/7)+(-7/9+ 7/9)+(9/11- 9/11)+(- 11/13+11/13)+13/15
    = 13/15
    e. 1/2014 – 1/(2014.2013) – 1/(2013.2012) -….- 1/(3.2) – 1/(2.1)
    = 1/2014- (2014/(2014.2013)-2013/(2014.2013))-…- (2/(2.1)-1/(2.1))
    = 1/2014-(1/2013-1/2014)-(1/2012-1/2013)-…-(1-1/2)
    = 1/2014+1/2014-1/2013+1/2013-1/2012+…+1/2-1
    = 1/1007 – 1
    = (-1006)/1007
    Bài 2:
        -4/7 – x = 3/5 – 2x
    ⇔ -x+2x = 3/5+4/7
    ⇔ x = 41/35
     

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

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