Bài 1: 

a) \(\dfrac{65}{91}+\dfrac{-33}{55}=\dfrac{5}{7}+\dfrac{-3}{5}=\dfrac{25}{35}+\dfrac{-21}{35}=\dfrac{4}{35}\)

b) \(\dfrac{36}{-84}+\dfrac{100}{450}=\dfrac{-3}{7}+\dfrac{2}{9}=\dfrac{-27}{63}+\dfrac{14}{63}=\dfrac{-13}{63}\)

d) \(\left(\dfrac{1}{2}-\dfrac{1}{3}\right)\left(5-\dfrac{1}{4}\right)=\dfrac{1}{6}\cdot\dfrac{19}{4}=\dfrac{19}{24}\)

e) \(\dfrac{2}{3}-4\left(\dfrac{1}{2}+\dfrac{3}{4}\right)=\dfrac{2}{3}-2-3=\dfrac{2}{3}-\dfrac{15}{3}=\dfrac{-13}{3}\)

1 : 95

2 : 9

3 : D 

ok nhé 

Thank you các bạn đã giúp mình !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

95;9;D

Bài 1 :

a) \(...=45\left(56+44\right)-500=45.100-500=4500-500=4000\)

b) \(...=3^2.6-6^{18}+1=45+1-6^{18}=46-6^{18}\)

c) \(...=756\left(66+48-14\right)=756.100=75600\)

d) \(...=8.15-\left(149-7^2\right)=120-\left(149-49\right)=120-100=20\)

Bài 2 :

a) \(x-21=46\Rightarrow x=21+46\Rightarrow x=87\)

b) \(2^x.4=128\Rightarrow2^x=32\Rightarrow2^x=2^5\Rightarrow x=5\)

c) \(3x+27=162\Rightarrow3x=162-27\Rightarrow3x=135\Rightarrow x=45\)

d) \(4x-8=4^{2023}.4^{2021}\)

\(\Rightarrow4x-8=4^{2023+2021}\)

\(\Rightarrow4x-8=4^{4044}\)

\(\Rightarrow4x=4^{4044}+8\)

\(\Rightarrow x=\left(4^{4044}+8\right):4\)

\(\Rightarrow x=4^{4043}+2\)

Bài 3 :

Số học sinh góp 20000 đồng là :

\(35-\left(1+3\right)=31\left(hsinh\right)\)

Tổng số tiền lớp 6a ủng hộ là :

\(1.100000+3.40000+31.20000=840000\left(đồng\right)\)

Đáp số...

\(a)4(15-18)-(3-5).(-3)^2\)

\(=4.\left(-3\right)-2.9\)

\(=6\)

\(b)(-4-11):(-3)\)

\(=-15:\left(-3\right)\)

\(=5\)

\(c)143-(-57)-(-2)^3.(-3)^0\)

\(=143+57+8.1\)

\(=208\)

\(d,\left(-5\right).\left[\left(90-2.5\right)-10^2+10:\left|-2\right|\right]\)

\(=-5.\left[80-100+10:2\right]\)

\(=-5.-15\)

\(=75\)

a) 2 x 2 = 4              3 x 3 = 9

2 x 4 = 8              3 x 5 = 15

2 x 6 = 12              3 x 7 = 21

2 x 8 = 16              3 x 9 = 27

4 x 4 = 16              5 x 5 = 25

4 x 2 = 8              5 x 7 = 35

4 x 6 = 24              5 x 9 = 45

4 x 8 = 32              5 x 3 = 15

b) 200 x 4 = 800              300 x 2 = 600

200 x 2 = 400             300 x 3 = 900

400 x 2 = 800             500 x 1 = 500

100 x 4 = 400             100 x 3 = 300

Trả lời 1 câu thôi nhé em 100 nhân 4 bằng 400 nhá em

a) 2 x 2 =4 ......              3 x 3 = ..9....

2 x 4 = ....8..              3 x 5 = ...15...

2 x 6 = ....12..              3 x 7 = .21.....

2 x 8 = ..16....              3 x 9 = ..27....

4 x 4 = ...16...              5 x 5 = ...25...

4 x 2 = ...8...              5 x 7 = ..35....

4 x 6 = .....24.              5 x 9 = .45.....

4 x 8 = ..32....              5 x 3 = .15.....

b) 200 x 4 = 800......              300 x 2 =600 ......

200 x 2 = ..400....             300 x 3 = 900......

400 x 2 = .....800.             500 x 1 = ..500....

100 x 4 = ....400..             100 x 3 = .300.....

help me pls