\(\frac{7}{4}-x+\frac{4}{3}=\frac{5}{19}\)

\(\Rightarrow\frac{7}{4}-x=\frac{5}{19}-\frac{4}{3}\)

\(\Rightarrow\frac{7}{4}-x=-\frac{61}{57}\)

\(\Rightarrow x=\frac{7}{4}+\frac{61}{57}\)

\(\Rightarrow x=???\)

tíc mình nha

x-4/5=5/2x4/15

x-4/5=2/3

x=2/3+4/5

x=8/15

(dấu / là dấu bằng giữa tử và mẫu)

\(x-\frac{4}{5}=\frac{5}{2}x\frac{4}{15}\)

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

\(x=\frac{2}{3}+\frac{4}{5}\)

\(x=\frac{22}{15}\)

nha bn

\(x-\frac{4}{5}=\frac{5}{2}\times\frac{4}{15}\)

\(x-\frac{4}{5}=\frac{20}{30}\)

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

\(x=\frac{2}{3}+\frac{4}{5}\)

\(x=\frac{22}{15}\)

1.Vì  \(\frac{x}{-2}=\frac{-8}{x}\Rightarrow-2.\left(-8\right)=x.x\)

                                        \(16=x.x\)hay \(4^2=x^2\Rightarrow x=4\)

2. Rút gọn : \(\frac{20}{28}=\frac{5}{7}=\frac{-5}{-7}\)

\(\Rightarrow x=-7\)

3. \(\frac{x}{2}-\frac{11}{5}=\frac{7}{8}\times\frac{64}{49}\)

\(\frac{x}{2}-\frac{11}{5}=\frac{8}{7}\)

Mà \(\frac{8}{7}+\frac{11}{5}=\frac{502}{35}\)

\(\Rightarrow x=\frac{234}{35}\)

1) \(\frac{x}{-2}=\frac{-8}{x}\)

\(\Rightarrow x\times x=\left(-2\right)\times\left(-8\right)\)

\(\Rightarrow x^2=16\)

\(\Rightarrow\orbr{\begin{cases}x^2=4^2\\x^2=\left(-4\right)^2\end{cases}\Rightarrow}\orbr{\begin{cases}x=4\\x=-4\end{cases}}\)

Vậy x = 4 hoặc x = -4

2) \(\frac{-5}{x}=\frac{20}{28}\)

\(\Rightarrow\frac{-5}{x}=\frac{5}{7}\)

\(\Rightarrow5\times x=\left(-5\right)\times7\)

\(\Rightarrow5\times x=-35\)

\(\Rightarrow x=\left(-35\right):5\)

\(\Rightarrow x=-7\)

Vậy x = -7

3) \(\frac{x}{2}-\frac{11}{5}=\frac{7}{8}\times\frac{64}{49}\)

\(\Rightarrow\frac{x}{2}-\frac{11}{5}=\frac{8}{7}\)

\(\Rightarrow\frac{x}{2}=\frac{8}{7}+\frac{11}{5}\)

\(\Rightarrow\frac{x}{2}=\frac{117}{35}\)

\(\Rightarrow35x=117\times2\)

\(\Rightarrow35x=234\)

\(\Rightarrow x=234:35\)

\(\Rightarrow x=\frac{234}{35}\)

Vậy  \(x=\frac{234}{35}\)

4) \(\frac{x}{5}+\frac{9}{2}=\frac{6}{7}\times\frac{36}{48}\)

\(\Rightarrow\frac{x}{5}+\frac{9}{2}=\frac{9}{14}\)

\(\Rightarrow\frac{x}{5}=\frac{9}{14}-\frac{9}{2}\)

\(\Rightarrow\frac{x}{5}=\frac{-27}{7}\)

\(\Rightarrow7x=\left(-27\right)\times5\)

\(\Rightarrow7x=-135\)

\(\Rightarrow x=\left(-135\right):7\)

\(\Rightarrow x=\frac{-135}{7}\)

Vậy  \(x=\frac{-135}{7}\)

5) \(\frac{3}{x-5}=\frac{-4}{x+2}\)

\(\Rightarrow\frac{3}{x-5}+\frac{4}{x+2}=0\)

\(\Rightarrow3\left(x+2\right)+4\left(x-5\right)=0\)

\(\Rightarrow3x+6+4x-20=0\)

\(\Rightarrow\left(3x+4x\right)+\left(6-20\right)=0\)

\(\Rightarrow7x-14=0\)

\(\Rightarrow7x=14\)

\(\Rightarrow x=14:7\)

\(\Rightarrow x=2\)

Vậy x = 2

_Chúc bạn học tốt_

\(1.\frac{x}{-2}=\frac{-8}{x}\)

\(\Rightarrow x\times x=\left(-8\right)\times\left(-2\right)\)

           \(x^2=16\)

        \(\Rightarrow x=4\)

       Vậy\(x=4\)

\(2.\frac{-5}{x}=\frac{20}{28}\)

\(\frac{-5}{x}=\frac{5}{7}\)

\(\frac{-5}{x}=\frac{-5}{-7}\)

  \(\Rightarrow x=-7\)

 Vậy\(x=-7\)

\(3.\frac{x}{2}-\frac{11}{5}=\frac{7}{8}\times\frac{64}{49}\)

    \(\frac{x}{2}-\frac{11}{5}=\frac{8}{7}\)

                 \(\frac{x}{2}=\frac{8}{7}+\frac{11}{5}\)

                 \(\frac{x}{2}=\frac{40+77}{35}\)

                 \(\frac{x}{2}=\frac{117}{35}\)

         \(x\times35=117\times2\)

               \(35x=234\)

                    \(x=\frac{234}{35}\)

              Vậy\(x=\frac{234}{35}\)

\(4.\frac{x}{5}+\frac{9}{2}=\frac{6}{7}\times\frac{36}{48}\)

   \(\frac{x}{5}+\frac{9}{2}=\frac{6}{7}\times\frac{3}{4}\)

   \(\frac{x}{5}+\frac{9}{2}=\frac{9}{14}\)

              \(\frac{x}{5}=\frac{9}{14}-\frac{9}{2}\)

             \(\frac{x}{5}=\frac{9}{14}-\frac{63}{14}\)

             \(\frac{x}{5}=\frac{-54}{14}\)

             \(\frac{x}{5}=\frac{-27}{7}\)

             \(7x=\left(-27\right)\times5\)

             \(7x=-135\)

               \(x=\frac{-135}{7}\)

         Vậy\(x=\frac{-135}{7}\)

\(5.\frac{3}{x-5}=\frac{-4}{x+2}\)

\(3\times\left(x+2\right)=\left(-4\right)\times\left(x-5\right)\)

           \(3x+6=\left(-4\right)x+20\)

        \(3x+4x=20-6\)

                  \(7x=14\)

                    \(x=14\div7\)

                    \(x=2\)

              Vậy\(x=2\)

\(\left(x+5\right)\left(x+4\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x+5=0\\x+4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-5\\x=-4\end{cases}}}\)

vậy x=-5 và x=-4

b) dễ tự làm

c)\(|x+9|-3=5\)

\(|x+9|=2\)

\(\Leftrightarrow\orbr{\begin{cases}x+9=2\\x+9=-2\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-7\\x=7\end{cases}}}\)

vậy x=-7 hoặc x=7

1/3 công 2/5= 5/15 cộng với 6/15=11/15

NẾU ĐÚNG CHO MÌNH ĐÚNG NHÉ.

NẾU SAI CHO MÌNH SAI. CẢM ƠN CÁC BẠN. THANK 

Bài làm

a) 1/3 + 2/5 = 5/15 + 6/15 = 11/15

b) 5/2 - 3/2 = 2/2 = 1

c) 1/2 x 2/4 = 1/4

d) 9/5 : 6/2 = 9/5 x 2/6 = 18/30 = 3/5

Bài 2

a) ( x + 5 )( x + 4 ) = 0

=> x + 5 = 0 hoặc x + 4 = 0

=> x = -5 hoặc x = -4

Vậy x = -5 hoặc x =-4

b) 2x + 48 = 96

=> 2x = 48

=> x = 24

Vậy x = 24

c) | x + 9 | - 3 = 5

=> | x + 9 | = 8

=> x + 9 = 8 hoặc x + 9 = -8

=> x = -1 hoặc x = -17

Vậy x = -1 hoặc -17

Mình làm như thế này nek

\(\frac{\frac{1}{4}+\frac{3}{7}-\frac{4}{5}}{0,75+\frac{9}{7}-2\frac{2}{5}}+\frac{\frac{3}{14}-\frac{2}{10}+\frac{5}{18}+\frac{7}{66}}{\frac{6}{7}-\frac{4}{5}+\frac{10}{9}+\frac{14}{33}}\)

\(=\frac{\frac{1}{4}+\frac{3}{7}-\frac{4}{5}}{\frac{2}{4}+\frac{9}{7}-\frac{12}{5}}+\frac{\frac{1}{2}\cdot\left(\frac{3}{7}-\frac{2}{5}+\frac{5}{9}+\frac{7}{33}\right)}{2\cdot\left(\frac{3}{7}-\frac{2}{5}+\frac{5}{9}+\frac{7}{33}\right)}\)

\(=\frac{\frac{1}{4}+\frac{3}{7}-\frac{4}{5}}{3\cdot\left(\frac{1}{4}+\frac{3}{7}-\frac{4}{5}\right)}+\frac{\frac{1}{2}}{2}\)

\(=\frac{1}{3}+\frac{1}{4}=\frac{7}{12}\)

== bài dễ , cậu giỏi sao giờ nằm viện mà ======== :v

Ta có:

\(\left(\frac{x+2}{327}+1\right)+\left(\frac{x+3}{326}+1\right)+\left(\frac{x+4}{325}+1\right)+\left(\frac{x+5}{324}+1\right)=\left(-4\right)+1+1+1+1\)

\(\Rightarrow\frac{x+329}{327}+\frac{x+329}{326}+\frac{x+329}{325}+\frac{x+329}{324}=0\)

\(\Rightarrow\left(x+329\right)\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}\right)=0\)

Mà \(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}\ne0\)

\(\Rightarrow x+329=0\)

\(\Rightarrow x=-329\)

Ta có : \(\frac{x+329-327}{327}+\frac{x+329-326}{326}+\frac{x+329-325}{325}+\frac{x+329-324}{324}\)

\(\Rightarrow\frac{x+329}{327}-1+\frac{x+329}{326}-1+\frac{x+329}{325}-1+\frac{x+329}{324}-1=-4\)

\(\Leftrightarrow\frac{x+329}{327}+\frac{x+329}{326}+\frac{x+329}{325}+\frac{x+329}{324}=0\)

\(\Rightarrow\left(x+329\right).\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}\right)=0\)

\(\Rightarrow x+329=0\Rightarrow x=-329\)

a)  \(=\frac{1}{1.3}.\frac{3.3}{2.4}.\frac{4.4}{3.5}.\frac{5.5}{4.6}.\frac{6.6}{5.7}=\frac{6}{2.7}=\frac{3}{7}\)

B) \(=\frac{70}{11}+\frac{1}{9}-\frac{37}{11}-\frac{1}{9}=\left(\frac{70}{11}-\frac{37}{11}\right)+\left(\frac{1}{9}-\frac{1}{9}\right)=\frac{33}{11}+0=3\)

BÀI 2:

A) \(\Leftrightarrow\frac{7}{2}x-\frac{x}{2}+\frac{2x}{2}=\frac{7}{2}.\frac{5}{6}\)

\(\Leftrightarrow\frac{7x-x+2x}{2}=\frac{35}{12}\)

\(\Leftrightarrow\frac{8x}{2}=\frac{35}{12}\)

\(\Leftrightarrow8x.12=35.2\Leftrightarrow96x=70\Leftrightarrow x=\frac{70}{96}=\frac{35}{48}\)

b) \(\left(x-\frac{3}{1.2}\right)+\left(x-\frac{3}{2.3}\right)+...+\left(x-\frac{3}{99.100}\right)=1\)

\(x-\frac{3}{1.2}+x-\frac{3}{2.3}+....x+\frac{3}{99.100}=1\)

\(\Leftrightarrow\left(x+x+x+...+x\right)-3\left(\frac{1}{1.2}+\frac{1}{1.3}+....+\frac{1}{99.100}\right)=1\)

ngoặc 1 có 99 số hạng x

\(\Leftrightarrow99x-3\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+....+\frac{1}{99}-\frac{1}{100}\right)=1\)

\(\Leftrightarrow99x-3\left(1-\frac{1}{100}\right)=1\)

\(\Leftrightarrow99x-3.\frac{99}{100}=1\)

\(\Leftrightarrow99x=1+\frac{3.99}{100}\)

\(\Leftrightarrow99x=\frac{397}{100}\)

\(\Leftrightarrow x=\frac{397}{100.99}=\frac{397}{9900}\)

ĐKXĐ: \(x\ge0;x\ne4.\)

\(A=\frac{x}{x-4}+\frac{1}{\sqrt{x}-2}+\frac{1}{\sqrt{x}+2}.\)

\(=\frac{x}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}+\frac{\sqrt{x}+2}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}+\frac{\sqrt{x}-2}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}\)

\(=\frac{x+\sqrt{x}+2+\sqrt{x}-2}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}=\frac{x+2\sqrt{x}}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}.\)

\(=\frac{\sqrt{x}\left(\sqrt{x}+2\right)}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}=\frac{\sqrt{x}}{\sqrt{x}-2}.\)

b) Để \(A=\frac{5}{4}\)\(\Leftrightarrow\frac{\sqrt{x}}{\sqrt{x}-2}=\frac{5}{4}\Leftrightarrow\frac{4\sqrt{x}}{4\left(\sqrt{x}-2\right)}-\frac{5\left(\sqrt{x}-2\right)}{4\left(\sqrt{x}-2\right)}=0\)

\(\Leftrightarrow\frac{4\sqrt{x}-5\sqrt{x}+10}{4\left(\sqrt{x}-2\right)}=0\Leftrightarrow-\sqrt{x}+10=0\)

\(\Leftrightarrow\sqrt{x}=10\Leftrightarrow x=100\left(tmđk\right).\)

Vậy để A=5/4 thì x=100

Tự tìm ĐK nha

a) \(A=\frac{x}{x-4}+\frac{1}{\sqrt{x}-2}+\frac{1}{\sqrt{x}+2}\)

\(A=\frac{x}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}+\frac{\sqrt{x}+2}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}+\frac{\sqrt{x}-2}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}\)

\(A=\frac{x+\sqrt{x}+2+\sqrt{x}-2}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}\)

\(A=\frac{x+2\sqrt{x}}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}\)

\(A=\frac{\sqrt{x}\left(\sqrt{x}+2\right)}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}\)

\(A=\frac{\sqrt{x}}{\sqrt{x}-2}\)

b) \(A=\frac{5}{4}\Leftrightarrow\frac{\sqrt{x}}{\sqrt{x}-2}=\frac{5}{4}\)

\(\Leftrightarrow4\sqrt{x}=5\left(\sqrt{x}-2\right)\)

\(\Leftrightarrow4\sqrt{x}=5\sqrt{x}-10\)

\(\Leftrightarrow\sqrt{x}=10\)

\(\Leftrightarrow x=100\)( thỏa mãn )

Vậy...

\(=\frac{5}{4}.\left(-\frac{1}{3}+-\frac{1}{3}+\frac{3}{7}+\frac{4}{7}\right)=\frac{5}{4}.0=0\)

\(=\frac{9}{5}\left(-\frac{3}{22}+-\frac{3}{5}\right)=-\frac{729}{550}\)