a) \(\frac{34}{13}=2\frac{8}{13}\)

Vì 2 > 1 nên \(2\frac{8}{13}>1\frac{7}{9}\)

hay \(\frac{34}{13}>1\frac{7}{9}\)

b) \(\frac{7}{9}=1-\frac{2}{9}\)

\(\frac{13}{15}=1-\frac{2}{15}\)

Vì \(\frac{2}{9}>\frac{2}{15}\) nên \(\frac{7}{9}< \frac{13}{15}\)

a) Ta có:

\(1\frac{7}{9}=\frac{16}{9}=\frac{208}{117}\) 

\(\frac{34}{13}=\frac{306}{117}\)

Vì \(306>208\)

\(\Rightarrow\frac{306}{117}>\frac{208}{117}\)

\(\Rightarrow\frac{34}{13}>1\frac{7}{9}\)

b) Ta có:

\(\frac{7}{9}=\frac{35}{45}\)

\(\frac{13}{15}=\frac{39}{45}\)

Vì \(39>35\)

\(\Rightarrow\frac{39}{45}>\frac{35}{45}\)

\(\Rightarrow\frac{13}{15}>\frac{7}{9}\)

a) Ta có:

\(\frac{3}{14}=\frac{15}{70}\)

\(\frac{5}{16}=\frac{15}{48}\)

Vì \(48< 70\)

\(\Rightarrow\frac{15}{48}>\frac{15}{70}\)

\(\Rightarrow\frac{5}{16}>\frac{3}{14}\)

b) Vì \(11< 12\)

\(\Rightarrow\frac{7}{11}>\frac{7}{12}\)

giúp mình đi 

Đặt A=\(\frac{7}{3}+\frac{11}{3^2}+\frac{15}{3^3}+\frac{19}{3^4}+...+\frac{2015}{3^{503}}+\frac{2019}{3^{504}}\)

3A=\(7+\frac{11}{3}+\frac{15}{3^2}+\frac{19}{3^3}+...+\frac{2015}{3^{502}}+\frac{2019}{5^{503}}\)

=> 3A-A=(\(7+\frac{11}{3}+\frac{15}{3^2}+\frac{19}{3^3}+...+\frac{2015}{3^{502}}+\frac{2019}{5^{503}}\))-(\(\frac{7}{3}+\frac{11}{3^2}+\frac{15}{3^3}+\frac{19}{3^4}+...+\frac{2015}{3^{503}}+\frac{2019}{3^{504}}\))

2A=\(7+\left(\frac{11}{3}-\frac{7}{3}\right)+\left(\frac{15}{3^2}-\frac{11}{3^2}\right)+\left(\frac{19}{3^3}-\frac{15}{3^3}\right)+...+\left(\frac{2019}{3^{503}}-\frac{2015}{3^{503}}\right)-\frac{2019}{3^{504}}\)

2A=\(7+\frac{4}{3}+\frac{4}{3^2}+\frac{4}{3^3}+...+\frac{4}{3^{503}}-\frac{2019}{3^{504}}\)

=> A=\(\frac{7}{2}+2\left(\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{503}}\right)-\frac{2019}{2.3^{504}}\)

Em làm tiếp Xét 

B=\(\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{503}}\)

3B=\(1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{502}}\)

=> 3B-B=\(1-\frac{1}{3^{503}}\)

=> B=\(\frac{1}{2}-\frac{1}{2.3^{503}}\)

=> A=\(\frac{7}{2}+2\left(\frac{1}{2}-\frac{1}{2.3^{503}}\right)-\frac{2019}{2.3^{504}}=\frac{9}{2}-\frac{1}{3^{503}}-\frac{2019}{2.3^{504}}< \frac{9}{2}\)

Vì đa thức f(x) có nghiệm là 1/2

=>  x = 1/2

Ta có

f(x) = 0

m.x - 3 = 0

m.1/2 - 3 = 0

m. 1/2 = 3

m = 3 : 1/2

m = 6

VẬY:.................

thanks nha nhưng mik vừa nghĩ ra òi

nhưng dù sao cx cảm ơn

3 + 4 = 7

7 : (4-3) x 4 = 28

28 x 4 = 112

đáp số 112 km

n

người ta viết các số tự nhiên từ 1 như sau

                                   1

                                2 3 4

                             5 6 7 8 9

                  10 11 12 13 14 15 16

Hỏi số thứ 84 từ trái sang phải của dòng 45 là số nào ?

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

b,\(\frac{-21}{10}+\frac{21}{10}.\frac{5}{7}=-\frac{21}{10}+\frac{105}{70}=-\frac{21}{10}+\frac{15}{10}=-\frac{6}{10}\)

a,\(\frac{-2}{3}+\frac{1}{5}=\frac{-2.5}{3.5}+\frac{3.1}{3.5}=-\frac{10}{15}+\frac{3}{15}=-\frac{7}{15}\)

b,\(3\frac{11}{13}-5\frac{11}{3}=3+\frac{11}{13}-(5+\frac{11}{13})=\left(3-5\right)+\left(\frac{11}{13}-\frac{11}{13}\right)=-2+0=-2\)

c,\(1\frac{2}{3}:(-\frac{5}{3})=\frac{5}{3}:\left(-\frac{5}{3}\right)=\frac{5.3}{3.\left(-5\right)}=\frac{15}{-15}=-1\)

d,\(\frac{31}{17}+\frac{-5}{13}+\frac{-8}{13}-\frac{14}{17}=\left(\frac{31}{17}-\frac{14}{17}\right)+\left(\frac{-5}{13}+\frac{-8}{13}\right)=1+\left(-1\right)=0\)

Tìm x:

a,x+12=8

x=8-12

x=-4

b,\(\frac{2}{3}x+\frac{1}{2}=\frac{1}{10}\)

\(\frac{2}{3}x=\frac{1}{10}-\frac{1}{2}\)

\(\frac{2}{3}x=\frac{1}{10}-\frac{5}{10}\)

\(\frac{2}{3}x=\frac{2}{5}\)

\(x=\frac{2}{5}:\frac{2}{3}\)

\(x=\frac{6}{10}\)

\(x=\frac{3}{5}\)

a) \(\frac{-2}{3}+\frac{1}{5}=\frac{-10}{15}+\frac{3}{15}=\frac{-10+3}{15}=\frac{-7}{15}\)

b) \(3\frac{11}{13}-5\frac{11}{13}=\frac{50}{13}-\frac{76}{13}=\frac{50-76}{13}=\frac{-26}{13}=-2\)

c) \(1\frac{2}{3}:\frac{-5}{3}=\frac{5}{3}:\frac{-5}{3}=\frac{5}{3}\times\frac{3}{-5}=\frac{15}{-15}=-1\)

d) \(\frac{31}{17}+\frac{-5}{13}+\frac{-8}{13}-\frac{14}{17}\)

\(=\left(\frac{31}{17}-\frac{14}{17}\right)+\left(\frac{-5}{13}+\frac{-8}{13}\right)\)

\(=\left(\frac{31-14}{17}\right)+\left(\frac{-5-8}{13}\right)\)

\(=\frac{17}{17}+\frac{-13}{13}\)

\(=1+\left(-1\right)\)

\(=0\)

TÌM x

a)   \(x+12=8\)

\(\Leftrightarrow x=8-12\)

\(\Leftrightarrow x=-4\)

b)   \(\frac{2}{3}x+\frac{1}{2}=\frac{1}{10}\)

\(\Leftrightarrow\frac{2}{3}x=\frac{1}{10}-\frac{1}{2}=\frac{1}{10}-\frac{5}{10}=\frac{1-5}{10}\)

\(\Leftrightarrow\frac{2}{3}x=\frac{-4}{10}=\frac{-2}{5}\)

\(\Leftrightarrow x=\frac{-2}{5}:\frac{2}{3}=\frac{-2}{5}\times\frac{3}{2}\)

\(\Leftrightarrow x=\frac{-6}{10}=\frac{-3}{5}\)

Nếu A chia hết cho 4

=> A có dạng 4k= 2 x 2 x k => chia hết cho 2 (k là số tự nhiên khác 0)

Vậy số dư khi chia A cho 2 là 0.

T**k mik nhé!

hok tốt!

If A is divisible by 4, then the remainder of A : 2 is 0

OK