Câu 1:

A={1;3;5;7;9}

Câu 2: 

A. 24 x 82 + 24 x 18 - 100 

= 24 x (82 + 18) - 100

= 24 x 100 - 100

= 2400 - 100 = 2300

B.12 + 3 [ 39 - (5 - 2 )² ]

= 12 + 3. [39 - 3² ]

= 12 + 3 . [39-9]

= 12 + 3.30

= 12 + 90 = 102

Câu 14: 

a. \(\text{3 + x = - 8}.\) \(\Leftrightarrow x=-8-3=-11.\)

b. \(\text{(35 + x) - 12 = 27}.\) 

\(\Leftrightarrow35+x=27+12.\)

\(\Leftrightarrow35+x=39.\Leftrightarrow x=39-35=14.\)

c. \(2^x+15=31.\) 

\(\Leftrightarrow2^x=16.\)

\(\Leftrightarrow2^x=2^4.\)

\(\Leftrightarrow x=4.\)

\(b,\left(-26\right)+16+\left(-34\right)+26=\left(-10\right)+\left(-8\right)=-18\\ c,12+3.\left[39-\left(5-2\right)^2\right]\\ =12+3.\left[39-3^2\right]\\ =12+3.\left[39-9\right]\\ =12+3.30\\ =12+90=102\)

b) (-26)+16+(-34)+26

=16-34

=-18

c)12+3[39-(5-2)²]

=12+3[39-(25-20+4)]

=12+3[39-9]

=12+3.30

=12+90

=102

\(26+\left(-16\right)+\left(-34\right)+26\)

\(=26+\left[\left(-16\right)+\left(-34\right)\right]\)

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

\(=-24\)

\(12+3.\left[39-9\right]\)

\(=12+3.30\)

\(=12+90\)

\(=102\)

1/ 35. 18 – 5. 7. 28

= 35.(18-28)

=35.-10

=-350

2/ 45 – 5. (12 + 9)

=5.(9-12-9)

=5.-12

=-60

3/ 24. (16 – 5) – 16. (24 - 5)

= 24.16-24.5-16.24+16.5

=-24.5+16.5

=(-24+16).5

=-8.5

=-40

1, 35(18-28)=35.(-10)=-350

2, 45-30-45=-30

3, 24.16-24.5-16.24+16.5 = 16.5-24.5 = -40

\(\text{ 35 . 18 - 5 . 7 . 28 = 35 . 18 - 35 . 28}\)

\(\text{= 35 . (18 - 28)}\)

\(\text{= 35 . (-10)}\)

\(\text{= -350}\)

\(\text{45 - 5 . (12 + 9) = 45 - 5 . 9 + 5 . 12}\)

\(\text{= 45 - 45 + 60}\)

\(\text{= 60}\)

\(\text{24 . (16 - 5) - 16 . (24 - 5) = 24 . 16 - 24 . 5 - 16 . 24 + 16 . 5}\)

\(\text{= (24 . 16 - 16 . 24) + (16 . 5 - 24 . 5)}\)

\(\text{=0 + 5 . (16 - 24)}\)

\(\text{= 5. (-8)}\)

\(\text{= -40}\)

Em nến gõ bằng công thức toán học em nhé. Như vậy mọi người nới hiểu đúng đề bài để trợ giúp cho em một cách tốt nhất em ạ!

\(2575+37-2576-29\)

\(=2612-2576-29\)

\(=36-29=7\)'

\(35+35+36+37-14-15-16-17\)

\(=70+\left(36-16\right)+\left(37-17\right)-14-15\)

\(=70+20+20-14-15\)

\(=90+6-15\)

\(=96-15=81\)

\(13\cdot\left(-12\right)+87.\left(-12\right)\)

\(=\left(-12\right)\cdot\left(13+87\right)\)

\(=\left(-12\right)\cdot100=-1200\)

\(26\cdot17+17\cdot74\)

\(=\left(26+74\right)\cdot17\)

\(=100\cdot17=1700\)

\(25\cdot\left(-18\right)+25\left(-82\right)\)

\(=25\cdot\left[\left(-18\right)+\left(-82\right)\right]\)

\(=25\cdot\left(-100\right)=\left(-2500\right)\)

\(25+37-48-25-37\)

\(=\left(25-25\right)+\left(37-37\right)-48\)

\(=0+0-48\)

\(=0-48=\left(-48\right)\)

\(\left(-16\right)+24+16-34\)

\(=\left[\left(-16\right)+16\right]+\left(24-34\right)\)

\(=0+\left(-10\right)=\left(-10\right)\)

a) =-46
b) =0
c) =-2021
d) =-2400

a. -46

b. 0

c. 2021

d. -2400

Bài 2:

a. $=62-81-12+59-9=(62-12)+(59-9)-81$

$=50+50-81=100-81=19$

b. $=39+13-26-62-39=(39-39)+13-(26+62)$

$=0+13-88=-(88-13)=-75$

c. $=(32-42)+(36-34)+(40-38)=10+2+2=14$
d. $=92-55+8-45=(92+8)-(55+45)=100-100=0$

Bài 1:

a. $=(387-87)-224=300-224=76$

b. $=-(75+35)+379=-110+379=379-110=269$

c. $=(11+15)-(13+17)=25-30=-5$

d. $=(31-21)-(27-24)=10-3=7$

Mai mk gửi cho

Tính hợp lý : 

45-45.(-12+3)  

=45-45.(-9)

=45-(405)

=kết quả

31.(-18)+31.(-81)-31

=31.(-18)+31.(-81)-31.1

=31.[-18+(-81)+(-1)]

=31.(-100)

Kquả

24.(16-5)-16.(24-5)

=24.16-24.5-16.24-16.5

=(26.16-16.24)-24.5-16.5

=0-(24-16)5

=0-8.5

0-40

(-12).47+(-12).52+(-12).1

=-12.[47+52+1]

=-12.100

=-1200