Câu 2: a) 234-117+(-100)+(-234)=[234+(-234)]-117-100=0-117-100=-217

b) -927+1421+930+(-1421)=-927+930+[1421+(-1421)]=-927+930+0=3

Bài 1:

s1=1+(-3)+5+(-7)+............+17

s2=-2+4+(-6)+8+...........+(-18)
\(\Rightarrow\) s1 + s2 = (1-2-3+4)+(5-6-7+8)+...+(13-14-15+16)+17-18

= 0 + 0 + ...+ 0 + (-1)

= -1

Bài 2.

a) 234-117+(-100)+(-234)

= (-234 + 234 ) + [- 117 + (-100)]

= 0 + (-217)

= -217

b) -927+1421+930+(-1421)

= ( -1421 + 1421 ) + ( -927 + 930 )

= 0 + 3

= 3

   4 . 24 . 5 ^ 2 - ( 3 ^ 3 . 18 + 3 ^ 3 . 12 )

= 4 . 24 . 25    - ( 9  . 18 + 9 . 12 )

= ( 4 . 25 ) . 24 - 9 . ( 18 + 12 )

=      100   . 24 - 9 . 30

=        2400      - 270 

=            2130

\(4.24.5^2-\left(3^3.18+3^3.12\right)\)

=\(24.100-3^3\left(18+12\right)\)

=\(24000-270=23730\)

3^3= 27 nhé Phương Dung

a) 5.4² - 18 : 3² = 5.16 - 18 : 9 = 80 - 2 = 78

b) 3³.18 - 3³.12 = 3³(18 - 12) = 3³.6 = 27.6 = 162

c) 39.213 + 87.39 = 39.(213 + 87) = 39.300 = 11700

d) 80 - [130 - (12 - 4² )] = 80 - (130 - 12 + 4²) = 80 - 130 + 12 - 4² = -50 - 4 = -54

hết chịch

5.4^2 -18:3^2

=5.16 -18:9

=80-2

=78

3^3.18-3^3.12

=27.18-27.12

=27.(18-12)

=27.6

=162

39.213+87.39

=39.(213+87)

=39.300

=11700

80-[130-(12-4^2)]

=80-[130-(12-16)]

=80-[130-(-4)]

=80-134

=-54

2:

=>2y=30

=>y=15

3:

=1/2(9/7-4/7)+5/7*13/2

=5/7(1/2+13/2)

=5/7*7=5

\(\dfrac{12^3.18^2}{24^2}=\dfrac{12^3.6^2.3^2}{6^2.4^2}=\dfrac{4^3.3^3.3^2}{4^2}=4.3^3.3^2=4.3^5=972\)

\(\dfrac{12^3.18^2}{24^2}=\dfrac{1728.324}{576}=\dfrac{559872}{576}=972\)

Vậy giá trị cần tìm là 972

\(=\dfrac{\left(2^2\cdot3\right)^3\cdot\left(2\cdot3^2\right)^2}{\left(2^3\cdot3\right)^2}\)
\(=\dfrac{2^{2\cdot3}\cdot3^3\cdot2^2\cdot3^{2\cdot2}}{2^{3\cdot2}\cdot3^2}\)
\(=\dfrac{2^6\cdot2^2\cdot3^3\cdot3^4}{2^6\cdot3^2}\)
\(=2^2\cdot3^5\) \(=4\cdot243\) \(=486\)

dế quá

tích cho t đi

3.8.18+ 4.6.57+ 2.12.25

= 24.18+24.57+24.25

=24.( 18+ 57+25)

=24. 100=2400

= ( 3.8 ) .18 + ( 4.6 ) .57 + ( 2.12 ) .25

= 24.18 + 24.57 + 24.25

= 24 . ( 18 + 57 + 25 )

= 2400

#Ứng Lân

\(A=\frac{33\cdot10^3}{2^3\cdot5\cdot10^3+7000}=\frac{33\cdot10^3}{2^3\cdot5\cdot10^3+7\cdot10^3}=\frac{33\cdot10^3}{10^3(2^3\cdot5+7)}=\frac{33\cdot10^3}{10^3\cdot47}=\frac{33}{47}\)

\(B=\frac{3774}{5217}=\frac{34\cdot111}{47\cdot111}=\frac{34}{47}\)

\(=>\frac{33}{47}< \frac{34}{47}\)nên \(A< B\)

câu b nữa bn

Câu b,

\(M=\frac{1919.171717}{191919.1717}=\frac{19.101.17.10101}{19.10101.17.101}=1 \)

Vì \(1>\frac{18}{19}\)nên \(M>N\)

a. \(5,6\times2+2,8\times8+11,2\times2-48,5 \)

\(=5,6\times2+2,8\times4\times2+11,2\times2-48,5\)

\(=11,2\times1+11,2\times2+11,2\times2-48,5\)

\(=11,2\times\left(1+2+2\right)-48,5\)

\(=11,2\times5-48,5\)

\(=56-48,5\)

\(=7,5\)

b. \(0,8\times96+1,6\times2\)

= \(0,8\times96+0,8\times4\)

\(=0,8\times\left(96+4\right)\)

\(=0,8\times100\)

\(=80\)

Chúc cậu học tốt và nhớ thực hiện lời hứa với mình đó =)))))))