57 × 7/10 + 7/10 × 45 - 14/10

= 57 × 7/10 + 7/10 × 45 - 2 × 7/10

= 7/10 × (57 + 45 - 2)

= 7/10 × 100

= 70

57 × 7/10 + 7/10 × 45 - 14/10 = (57 × 7)/10 + (7/10) × 45 - 14/10 = 399/10 + (7/10) × 45 - 14/10 = 399/10 + (7 × 45)/10 - 14/10 = 399/10 + 315/10 - 14/10 = (399 + 315 - 14)/10 = 700/10 = 70

- Tính giá trị ở mỗi vế.

- So sánh rồi điền dấu thích hợp vào chỗ trống.

a) 32 + 7 < 40     b) 32 + 14 = 14 + 32

45 + 4 < 54 + 5     69 - 9 < 96 - 6

55 - 5 > 40 + 5     57 - 1 < 57 + 1

a) \(\left(-23\right)+13\left(-17\right)+57\)

\(=\left(-23\right)+\left(-221\right)+57\)

\(=-23-221+57\)

\(=-\left(23+221\right)+57\)

\(=-244+57\)

\(=-\left(244-57\right)\)

\(=-187\)

b) \(\left(-26\right)+\left(-6\right)+\left(-75\right)+\left(-50\right)\)

\(=-26-6-75-50\)

\(=-\left(26+6\right)-75-50\)

\(=-32-75-50\)

\(=-\left(32+75\right)-50\)

\(=-107-50\)

\(=-\left(107+50\right)\)

\(=-157\)

c) \(14+6+\left(-9\right)+\left(-14\right)\)

\(=14+6-9-14\)

\(=20-9-14\)

\(=11-14\)

\(=-3\)

d) \(\left(-123\right)+\left|13\right|+\left(-7\right)\)

\(=-123+13-7\)

\(=-\left(123-13\right)-7\)

\(=-110-7\)

\(=-\left(110+7\right)\)

\(=-117\)

e) \(\left|0\right|+\left|45\right|+\left(-\left|-455\right|\right)+\left|-796\right|\)

\(=0+45+\left(-455\right)-796\)

\(=45-455-796\)

\(=-410-796\)

\(=-\left(410+796\right)\)

\(=-1206\)

f) \(-\left|-33\right|+\left(-12\right)+18+\left|45-40\right|-57\)

\(=-33-12+18+\left|5\right|-57\)

\(=-\left(33+12\right)+18+5-57\)

\(=-45+18+5-57\)

\(=-\left(45-18\right)+5-57\)

\(=-27+5-57\)

\(=-\left(27-5\right)-57\)

\(=-22-57\)

\(=-\left(22+57\right)\)

\(=-79\)

(-23)+13(-17)+57

=(-23)-221+57

=218+57

=275

14+6+(-9)+(-14)

=20+(-9)+(-14)

=11+(-14)

=-3

\(1,=38-42+14-25+27+15=27\)

\(2,=12+21-23+21-10=21\)

\(3,=57-725-605+53=-1220\)

\(4,=55+45+15-15+55-45=110\)

\(\text{1.(38-42+14)-(25-27-15)}\\ =38-42+14-25+27+15\\ =-4-11+42\\ =27\)

\(\text{2.(12+21)-(23-21+10)}\\ =12+21-23+21-10\\ =33+44-10=67\)

Bài 1: 

b) (-17)+(-23)=-40

c) (-29)+36=7

d) 45+(-57)=-12

e) 105+(-5)=100

f) (-48)+(-14)=-62

g) (-75)+(-13)=-88

h) (-37)+23=-14

i) (-54)+(-46)=-100

biểu thức đâu

a: \(A=49+\dfrac{8}{23}-14-\dfrac{8}{23}-5-\dfrac{7}{32}=30-\dfrac{7}{32}=\dfrac{953}{32}\)

b:

Sửa đề: \(B=71\dfrac{38}{45}-\left(43\dfrac{8}{45}-1\dfrac{17}{51}\right)\)

 \(B=71+\dfrac{38}{45}-43-\dfrac{8}{45}+1+\dfrac{17}{51}\)

\(=71-43+1+1\)

=28+2=30

khó quá

a: \(A=49+\dfrac{8}{23}-14-\dfrac{8}{23}-5-\dfrac{7}{32}=30-\dfrac{7}{32}=\dfrac{953}{32}\)

b:

Sửa đề: \(B=71\dfrac{38}{45}-\left(43\dfrac{8}{45}-1\dfrac{17}{51}\right)\)

 \(B=71+\dfrac{38}{45}-43-\dfrac{8}{45}+1+\dfrac{17}{51}\)

\(=71-43+1+1\)

=28+2=30

Bài 1:

1: =15+37+52-37-17=52-2=50

2: =38-42+14-25+27+15=62-42+29=20+29=49

Bài 1: Bỏ ngoặc rồi tính

3) (21-32) - (-12+32)=21-32-(-12)-32=21-32+12-32=-31

4) (12+21) - (23-21+10)=12+21-23+21-10=21

5) (57-725) - (605-53)=57-725-605+53=-1220

6) (55+45+15) - (15-55+45)=55+45+15-15+55-45=55+55=110

Bài 2: Tính các tổng sau một cách hợp lí

1) (-37) + 14 + 26 + 37=(-37+37)+(14+26)=0+40=40

2) (-24) +6 + 10 + 24=(-24+24)+(6+10)=0+16=16

3) 15 + 23 + (-25) + (-23)=(15-25)+(23-23)=-10+0=-10

4) 60 + 33 + (-50) + (-33)=(60-50)+(33-33)=10+0=10

5) (-16) + (-209) + (-14) + 209=(-16-14)+(-209+209)=-30+0=-30

6) (-12) + (-13) + 36 + (-11)=(-11-12-13)+36=-36+36=0

=15+37+52-37-17 =(37-37)+52+15-17 =0+52+15-17 =67-17 =50

(38 – 42 + 14) – (25 – 27 – 15) =38-42+14-25+27+15 =27 c. -(21 – 32) – (-12 + 32) =-21+32+12-32 =-9 d. -(12 + 21 – 23) - (23 – 21 + 10) =-12-21+23-23+21-10 =-22 e. (57 – 725) – (605 – 53) =57-725-605+53 =-1220 f. (55 + 45 + 15) – (15 – 55 + 45) =55+45+15-15+55-45 =110