Ta có : \(\left(5x-3\right)\left(2x+5\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}5x-3=0\\2x+5=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}5x=3\\2x=-5\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=\frac{3}{5}\\x=-\frac{5}{2}\end{cases}}\)

Mình trả lời nha

a) 3 và 1/5.x=1 và 3/5+7/10

         16/5.x=8/5+7/10

         16/5.x=23/10

                x=23/10:16/5

                x=23/32

b)2 và 1/4(x-7 và 1/3)=1,5

               9/4(x-22/3)=3/2

                      x-22/3=3/2:9/4

                      x-22/3=2/3

                      x       =2/3+22/3

                      x       =8

****

a) \(\frac{31}{5}\).x = \(\frac{13}{5}\)+ \(\frac{7}{10}\)

31/5 . x = 33/10

x = 33/10 : 31/5

x = 33/62

b)  21/4 . ( x - 71/3 ) = 1,5

21/4 . (x- 71/3) = 3/2

x - 71/3 = 3/2 : 21/4

x - 71/3 = 2/7

x = 2/7 + 71/3

x = 503/21 

\(a)\frac{62}{7}\cdot x=\frac{29}{9}\div\frac{3}{56}\)

\(\Rightarrow\frac{62}{7}\cdot x=\frac{29}{9}\cdot\frac{56}{3}\)

\(\Rightarrow\frac{62}{7}\cdot x=\frac{1624}{27}\)

\(\Rightarrow x=\frac{1624}{27}\div\frac{62}{7}\)

\(\Rightarrow x=\frac{1624}{27}\cdot\frac{7}{62}\)

\(\Rightarrow x=\frac{11368}{1674}=\frac{5684}{837}\)

Rút gọn thử đi

\(=\left(\frac{x}{\left(x+2\right)\left(x-2\right)}-\frac{2}{x-2}+\frac{1}{x+2}\right):\left(\frac{\left(x-2\right)\left(x+2\right)+10-x}{x+2}\right)\)

\(=\left(\frac{x-2\left(x+2\right)+\left(x-2\right)}{\left(x+2\right)\left(x-2\right)}\right):\left(\frac{x^2-4+10-x}{x+2}\right)\)

Đổi 10-x lại thành\(10-x^2\) nha, mk thiếu! sorry!

\(=\left(\frac{x-2x-4+x-2}{\left(x+2\right)\left(x-2\right)}\right):\left(\frac{x^2-4+10-x^2}{x+2}\right)\)

\(=\frac{-6}{\left(x+2\right)\left(x-2\right)}.\frac{x+2}{6}\)

\(=\frac{-6\left(x+2\right)}{6\left(x-2\right)\left(x+2\right)}=-\frac{1}{x-2}\)

bài b bn chia ra 2 trường hợp x=1/2 hoặc -1/2 thay vào A lần lượt tính

Bài 1:

a) \(\frac{2}{5}+\frac{1}{5}.\left(\frac{3}{4}\right)\)

= \(\frac{2}{5}+\frac{3}{20}\)

= \(\frac{11}{20}\)

b) \(\frac{5}{12}.\left(-\frac{3}{4}\right)\) + \(\frac{7}{12}.\left(-\frac{3}{4}\right)\)

= \(\left(\frac{5}{12}+\frac{7}{12}\right).\left(-\frac{3}{4}\right)\)

= 1.\(\left(-\frac{3}{4}\right)\)

= \(-\frac{3}{4}\)

Còn câu c) đang nghĩ.

Bài 2:

a) \(\frac{5}{7}+\frac{2}{7}\)x = 1

1.x = 1

x = 1 : 1

x = 1

Vậy x = 1.

b) 0,2 + | x - 1, 3 = 1, 5|

0,2 + x = 1, 5 + 1, 3

0,2 + x = 2, 8

x = 2, 8 - 0, 2

x = 2, 6

Vậy x = 2, 6.

c) 2^x + 5 = 37

2^x = 37 - 5

2^x = 32

2^x = 2⁵

=> x = 5

Vậy x = 5.

d) 2^x + 2^{x + 1} = 48

2^x . 1 + 2^x . 2¹ = 48

2^x . ( 1 + 2) = 48

2^x . 3 = 48

2^x = 48 : 3

2^x = 16

2^x = 2⁴

=> x = 4

Vậy x = 4.

Chúc bạn học tốt!

làm bước trung gian giùm mình luôn nhé

thanks trước những bạn làm giùm nhé

mình đang cần gấp lắm sáng mai là mình cần ai đang on làm giùm mình nhé

thanks

Thuy Huynh mk làm nốt câu c bạn ấy chưa làm:

c/ \(\frac{2^{15}.9^4}{6^5.8^3}\)

\(=\frac{2^{15}.\left(3^2\right)^4}{\left(3.2\right)^5.\left(2^3\right)^3}\)

\(=\frac{2^{15}.3^8}{3^5.2^5.2^9}\)

\(=\frac{2^{15}.3^8}{3^5.2^{14}}\)

\(=2.3^3\)

= 2.27

= 54

a) Ta có: \(\frac{1}{2}+\frac{2}{3}:\left(x-1\right)=\frac{2}{3}\)

⇒\(\frac{2}{3}:\left(x-1\right)=\frac{2}{3}-\frac{1}{2}=\frac{1}{6}\)

⇒\(x-1=\frac{2}{3}:\frac{1}{6}=\frac{2}{3}\cdot6=4\)

hay x=5

Vậy: x=5

b) \(5,4-3\left[x-120\%\right]=\frac{3}{10}\)

⇔\(\frac{27}{5}-3\cdot\left(x-\frac{6}{5}\right)=\frac{3}{10}\)

⇔\(3\left(x-\frac{6}{5}\right)=\frac{27}{5}-\frac{3}{10}=\frac{51}{10}\)

hay \(x-\frac{6}{5}=\frac{51}{10}\cdot\frac{1}{3}=\frac{17}{10}\)

⇔\(x=\frac{17}{10}+\frac{6}{5}=\frac{29}{10}\)

Vậy: \(x=\frac{29}{10}\)

c) \(10\cdot3^{x+2}-3^x=89\)

\(\Leftrightarrow10\cdot3^2\cdot3^x-3^x=89\)

\(\Leftrightarrow3^x\left(90-1\right)=89\)

\(\Leftrightarrow3^x=1\)

hay x=0

Vậy: x=0

d) \(5\cdot\left(x-0,2\right)=3x+\left(\frac{-2}{3}\right)^3\)

⇒\(5\cdot\left(x-\frac{1}{5}\right)=3x+\frac{-8}{27}\)

\(\Leftrightarrow5x-1-3x-\frac{-8}{27}=0\)

\(\Leftrightarrow2x-\frac{19}{27}=0\)

\(\Leftrightarrow2x=\frac{19}{27}\)

hay \(x=\frac{\frac{19}{27}}{2}=\frac{19}{27}\cdot\frac{1}{2}=\frac{19}{54}\)

Vậy: \(x=\frac{19}{54}\)

e) \(\left(2x+\frac{3}{4}\right)^2-1,5=2\frac{1}{2}\)

\(\Leftrightarrow\left(2x+\frac{3}{4}\right)^2=\frac{5}{2}+\frac{3}{2}=\frac{8}{2}=4\)

\(\Leftrightarrow\left[{}\begin{matrix}2x+\frac{3}{2}=-2\\2x+\frac{3}{2}=2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=-2-\frac{3}{2}\\2x=2-\frac{3}{2}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=-\frac{7}{2}\\2x=\frac{1}{2}\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{-7}{2}\cdot\frac{1}{2}\\x=\frac{1}{2}\cdot\frac{1}{2}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{-7}{4}\\x=\frac{1}{4}\end{matrix}\right.\)

Vậy: \(x\in\left\{-\frac{7}{4};\frac{1}{4}\right\}\)

\(\frac{4}{7}\times x=\frac{1}{5}+\frac{2}{3}\)

\(\frac{4}{7}x=\frac{13}{15}\)

\(\Rightarrow x=\frac{91}{60}\)

các bài còn lại tương tự nha 

mấy cái này dễ mà toán tìm x này là cơ bản!!

67865785685685785785774677567568568

\(\frac{4}{7}\times x-\frac{2}{3}=\frac{1}{5}\)

\(\frac{4}{7}\times x=\frac{2}{3}+\frac{1}{5}\)

\(\frac{4}{7}\times x=\frac{13}{15}\)

\(x=\frac{13}{15}\div\frac{4}{7}\)

\(x=\frac{91}{60}\)