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

Toán Lớp 5: a , tính nhẩm 3/5+2= 2 3/5-2=

Toán Lớp 5: a , tính nhẩm
3/5+2= 2 3/5-2= 2-3/5
b , tính bằng cách thuận tiện nhất
2/5+3/4+1/4=
30/4-6/8-15/20=

Comments ( 2 )

  1. a ) 3/5 + 2 = 3/5 + 10/5 = {3 + 10}/5 = 13/5
    2 3/5 – 2 = 13/5 – 2 = 13/5 – 10/5 = {13 – 10}/5 = 3/5
    2 – 3/5 = 10/5 – 3/5 = {10 – 3}/5 = 7/5
    b ) 2/5 + 3/4 + 1/4 = 8/20 + 15/20 + 5/20 = {8 + 15 + 5}/20 = 28/20 = 7/5
    30/4 – 6/8 – 15/20 = 30/4 – 3/4 – 3/4 = {30 – 3 – 3}/4 = 24/4 = 6
    #dtkc
     

  2. a. tính nhẩm
    $\frac{3}{5}$ +2= $\frac{13}{5}$ 
    2 $\frac{3}{5}$ -2=$\frac{3}{5}$ 
    2-$\frac{3}{5}$ =$\frac{7}{5}$
    b. tính bằng cách thuận tiện nhất
    $\frac{2}{5}$ + $\frac{3}{4}$ + $\frac{1}{4}$
    = $\frac{2}{5}$ + 1
    = $\frac{7}{5}$
    $\frac{30}{4}$ – $\frac{6}{8}$ – $\frac{15}{20}$
    = $\frac{15}{2}$ – $\frac{3}{4}$ – $\frac{3}{4}$
    $\frac{15}{2}$ – ( $\frac{3}{4}$ + $\frac{3}{4}$ )               
    = $\frac{15}{2}$ – $\frac{6}{4}$
    =     7,5            –       1,5
    =              6
    Lunangoctrang1

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