a=1

b=2

c=3 

d=4 nha

\(=18x\left(\frac{19}{21}+\frac{8}{9}\right)\)

\(=18x\frac{113}{63}\)

\(=\frac{226}{7}\)

266/7

100,1< 64+45<111,1      <=>   x=4 

x = 4 nha bạn

vì 64+46=110

100,1<110<111,1

mình ra ròi abc=223

tích nhé ban

mình hỏi là abc bằng bao nhiêu chứ có hỏi a+b+c bằng bao nhiêu đâu bạn 

bạn lạc đề rùi

\(\overline{120ab}:376=\overline{ab}\)

\(\Rightarrow\overline{120ab}:\overline{ab}=376\)

\(\Rightarrow(12000+\overline{ab}):\overline{ab}=376\)

\(\Rightarrow12000:\overline{ab}+\overline{ab}:\overline{ab}=376\)

\(\Rightarrow12000:\overline{ab}+1=376\)

\(\Rightarrow12000:\overline{ab}=376-1\)

\(\Rightarrow12000:\overline{ab}=375\)

\(\Rightarrow\overline{ab}=12000:375\)

\(\Rightarrow\overline{ab}=32\)

a)>

b)<

c)>

d)>

e)<

g)<

Câu 8:

a) \(\frac{9}{14}>\frac{7}{14}\)

b) \(\frac{11}{18}<\frac{11}{14}\)

c) \(\frac{16}{15}>1\)

d) \(\frac{17}{25}>\frac35\)

e) \(\frac{6}{13}<\frac{13}{26}\)

g) \(\frac{17}{17}<\frac{19}{17}\)

Câu 9:

a) \(\frac38\) và \(\frac{19}{24}\)

Ta có: \(\frac38=\frac{3\times3}{8\times3}=\frac{9}{24}\)

Vì \(\frac{9}{24}<\frac{19}{24}\) nên \(\frac38<\frac{19}{24}\)

b) \(\frac{17}{20}\) và \(\frac25\)

Ta có: \(\frac25=\frac{2\times4}{5\times4}=\frac{8}{20}\)

Vì \(\frac{17}{20}>\frac{8}{20}\) nên \(\frac{17}{20}>\frac25\)

\(\frac{a}{b}.4+\frac{1}{6}=\frac{17}{6}\)

\(\frac{a}{b}.4\)          \(=\frac{17}{6}-\frac{1}{6}\)

\(\frac{a}{b}.4\)           \(=\frac{8}{3}\)

                      \(\frac{a}{b}=\frac{8}{3}:4\)

                      \(\frac{a}{b}=\frac{2}{3}\)

\(\frac{a}{b}.4=\frac{17}{6}-\frac{1}{6}\)

\(\frac{a}{b}.4=\frac{16}{6}\)

\(\frac{a}{b}=\frac{16}{6}:4\)

\(\frac{a}{b}=\frac{16}{6}.\frac{1}{4}=\frac{16}{6.4}=\frac{2}{3}\)

=2.3.4.5.6=720

a/

\(1\frac{1}{2}x1\frac{1}{3}x1\frac{1}{4}x1\frac{1}{5}x1\frac{1}{6}=\frac{3}{2}x\frac{4}{3}x\frac{5}{4}x\frac{6}{5}x\frac{7}{6}=\frac{7}{2}=3\frac{1}{2}\)

b/ 

x=0; y=5

\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}\)

\(=\frac{1}{2}.\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}\right)\)

\(=\frac{1}{2}.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}\right)\)

\(=\frac{1}{2}.\left(1-\frac{1}{9}\right)\)

\(=\frac{1}{2}.\frac{8}{9}\)

\(=\frac{4}{9}\)

Đặt: A=1/1.3+1/3.5+1/5.7+1/7.9

2A=2/1.3+2/3.5+2/5.7+2/7.9

2A=1-1/3+1/3-1/5+1/5-1/7+1/7-1/9

2A=1-1/9

2A=8/9

A=4/9

\(1+\frac{3}{4}+\frac{1}{6}\)

\(=\frac{12}{12}+\frac{9}{12}+\frac{2}{12}\)

\(=\frac{23}{12}\)

1 + 3/4 + 1/6

= 1 + 0,75 + 2/12

= 23/12