Đây là lớp 8 nha các b giúp mk với

Do mk viết nhầm

a/ \(\frac{15}{x}-\frac{1}{3}=\frac{28}{51}\)

\(\frac{15}{x}=\frac{28}{51}+\frac{1}{3}\)

\(\frac{15}{x}=\frac{15}{17}\)

\(x=15:\frac{15}{17}\)

\(x=17\)

b) \(\frac{x}{20}-\frac{2}{5}=10\)

\(\frac{x}{20}=10+\frac{2}{5}\)

\(\frac{x}{20}=\frac{52}{5}\)

\(x=\frac{52}{5}\cdot20\)

\(x=208\)

c) \(x+\frac{18}{23}=2\frac{1}{3}\)

\(x+\frac{18}{23}=\frac{7}{3}\)

\(x=\frac{7}{3}-\frac{18}{23}\)

\(x=\frac{107}{69}\)

d) \(\frac{7}{11}< x-\frac{1}{7}< \frac{10}{13}\)

\(\Rightarrow\frac{7}{11}+\frac{1}{7}< x< \frac{10}{13}\)

\(\frac{60}{77}< x< \frac{60}{78}\)

Đến đây .....bí!

e) Tớ bỏ luôn đc ko.

D) 7/11<X-1/7<10/13

    <=> 7/11+1/7<x< 10/13+1/7

 <=> 60/77< x< 83/91

<=> 5460/1001 <x< 6391/1001

vậy X thuộc tập hợp các phÂN số lớn hơn 5460/1001 và bé hơn 913/1001

vd :  Y/1001 trong đó y là 5461;5462;5463...6389;6390

\(-12;-9;-8;\frac{-7}{2};\frac{-21}{16};\frac{-11}{9};-\frac{1}{2}\)

5 mũ 37 ..... 11 mũ 24

so sánh

1.

a) 13\(\frac{1}{3}\) : 1\(\frac{1}{3}\) = 26 : (2x - 1)

<=> \(\frac{40}{3}:\frac{4}{3}\) = 13x - 26

<=> 10 + 26 = 13x

<=> 13x = 36

<=> x = \(\frac{36}{13}\)

b) 0,2 : 1\(\frac{1}{5}\) = \(\frac{2}{3}\) : (6x + 7)

<=> \(\frac{1}{5}:\frac{6}{5}\) = \(\frac{1}{9}x\) : \(\frac{2}{21}\)

<=> \(\frac{1}{6}\) = \(\frac{1}{9}x\) : \(\frac{2}{21}\)

<=> \(\frac{1}{9}x\) = \(\frac{2}{21}.\frac{1}{6}\) = \(\frac{1}{63}\)

<=> x = \(\frac{1}{7}\)

c) \(\frac{37-x}{x+13}\) = \(\frac{3}{7}\)

<=> (37 - x) . 7 = 3.(x + 13)

<=> 119 - 7x = 3x + 39

<=> -7x - 3x = 39 - 119

<=> -10x = -80

<=> x = 8

d) \(\frac{x-1}{x+5}=\frac{6}{7}\)

<=> 7(x - 1) = 6(x + 5)

<=> 7x - 7 = 6x + 30

<=> 7x - 6x = 30 + 7

<=> x = 37

e)

2\(\frac{2}{\frac{3}{0,002}}\) = \(\frac{1\frac{1}{9}}{x}\)

<=> \(\frac{1501}{750}\) = \(\frac{10}{9}:x\)

<=> x = \(\frac{10}{9}:\frac{1501}{750}\) = \(\frac{2500}{4503}\)

Bài 2. đề sai

Bài 3.

a) 6,88 : x = \(\frac{12}{27}\)

<=> x = 6,88 : \(\frac{12}{27}\)

<=> x = 15,48

b) 8\(\frac{1}{3}\) : \(11\frac{2}{3}\) = 13 : 2x

<=> \(\frac{25}{3}:\frac{35}{3}\) = 13 : 2x

<=> \(\frac{5}{7}=13:2x\)

<=> 2x = \(13:\frac{5}{7}\) = \(\frac{91}{5}\)

<=> x = 9,1

\(\Sigma\frac{b+1}{8-\sqrt{a}}\le\Sigma\frac{2\left(b+1\right)}{15-a}=\Sigma\frac{2\left(a+2b+c\right)}{4a+5b+5c}\)(AM-gm)

Đặt \(\left\{\begin{matrix}x=4a+5b+5c\\y=4b+5a+5c\\z=4c+5a+5b\end{matrix}\right.\)suy ra...

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