-3/8+12/25+5/-8+2/-5+13/25

=(3/8+5/-8)+12/25+2/-5+13/25

=-1+12/25+2/-5+13/25

=-13/25+2/-5+13/25

=-23/25+13/25

=-2/5

A=2/7+-3/8+11/7+1/3+1/7+5/-8

A=(2/7 + 1/7 + 11/7) + (-3/8 + 5/-8) + 1/3

A=2 + (-1) + 1/3

A=1 + 1/3

A=4/3

B=-3/8+12/25+5/-8+2/-5+13/25

B=(-3/8 + 5/-8) + (12/25 + 13/25) + 2/-5

B=-1 + 1 + 2/-5

B=-2/5

\(A=\frac{2}{7}+\left(-\frac{3}{8}\right)+\frac{11}{7}+\frac{1}{3}+\frac{1}{7}+\left(-\frac{5}{8}\right)\)

\(=\left(\frac{2}{7}+\frac{11}{7}+\frac{1}{7}\right)+\left(-\frac{3}{8}-\frac{5}{8}\right)+\frac{1}{3}\)

\(=2-1+\frac{1}{3}\)

\(=1+\frac{1}{3}\)

\(=\frac{4}{3}\)

\(B=-\frac{3}{17}+\left(\frac{2}{3}+\frac{3}{17}\right)\)

\(=-\frac{3}{17}+\frac{2}{3}+\frac{3}{17}\)

\(=\left(-\frac{3}{17}+\frac{3}{17}\right)+\frac{2}{3}\)

\(=0+\frac{2}{3}\)

\(=\frac{2}{3}\)

\(C=\frac{3}{8}+\frac{12}{25}+\frac{5}{-8}+\frac{2}{-5}+\frac{13}{25}\)

\(=\left(\frac{3}{8}-\frac{5}{8}\right)+\left(\frac{12}{25}+\frac{13}{25}\right)-\frac{2}{5}\)

\(=-\frac{1}{4}+1-\frac{2}{3}\)

\(=\frac{1}{12}\)

Đ/s : 2/3 nha bn

k cho mình nhé binn2011

\(A=\left(\dfrac{2}{7}+\dfrac{11}{7}+\dfrac{1}{7}\right)+\left(\dfrac{-3}{8}+\dfrac{-5}{8}\right)+\dfrac{1}{3}=2-1+\dfrac{1}{3}=1+\dfrac{1}{3}=\dfrac{4}{3}\)

\(B=\dfrac{-3}{8}+\dfrac{12}{25}+\dfrac{-5}{8}+\dfrac{-2}{5}+\dfrac{13}{25}=1+1-\dfrac{5}{8}=-\dfrac{5}{8}\)

A=2/7+-3/8+11/7+1/3+1/7+5/-8

=(2/7+11/7+1/7)+(-3/8-5/8)+1/3

=2+(-1)+1/3 =1+1/3 =4/3

B=-3/8+12/25+5/-8+2/-5+13/25

=(-3/8-5/8)+(12/25+13/25)-5/8

=-1+1-5/8= -5/8

2. Tính (+5) + ( +4) = 9

3.Tính (- 9) + ( - 1) = -10

4.Tính : 28 + (-15) = 13

5.Tính (-15) + 12 = - 3

6.Tính (-25) + 25 = 0

7.Tính : 13 - 17 = - 4

8.Tính : (-78) - 9 = - 87

9.Tính : ( -24) - ( - 16) = - 8

10.Tính : 17 - (-3) = 20

11.Tính nhanh : (-21) - ( 48 + 52 - 21) = -100

2,  (+5)+(+4)=+9 hoạc 9 cũng được

3,  (-9)+(-1)=-10

4,  28+(-15)=13

5,  (-15)+12=-3

6,  (-25)+25=0

7,  13-17=4

8,   (-78)-9=-87

9,  (-24)-(-16)=-40

10, 17-(-3)=20

11,  (-21+21)-(48-52)=-4

2.  (+5) + ( +4) = 9

3. (- 9) + ( - 1) = -10

4. 28 + (-15) = 13

5. (-15) + 12 = - 3

6. (-25) + 25 = 0

7. 13 - 17 = - 4

8. (-78) - 9 = - 87

9.( -24) - ( - 16) = - 8

10. 17 - (-3) = 20

11. (-21) - ( 48 + 52 - 21) = -100

a. bằng77

b. bằng 13

lớp 2 đã học cái này rồi à

a. bằng77

b. bằng 13

1)-73

2)-5

3)-64

4)-56

5)9

6)-20

7)6

8)-2

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