\(\frac{2}{3}+\frac{1}{3}:x=\frac{3}{5}\)

\(\Leftrightarrow\frac{1}{3x}=-\frac{1}{15}\)

\(\Leftrightarrow3x=-15\)

\(\Leftrightarrow x=-5\)

\(\frac{2}{3}+\frac{1}{3}\div x=\frac{3}{5}\)

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

\(\frac{1}{3}\div x=\frac{-1}{15}\)

\(x=\frac{1}{3}\div\frac{-1}{15}\)

\(x=-5\)

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

\(\Leftrightarrow\frac{3}{2}x-\frac{7}{3}x=\frac{3}{2}-\frac{2}{3}\)

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

\(\Leftrightarrow x=-1\)

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

\(\Leftrightarrow\left(\frac{3}{2}-\frac{7}{3}\right)x=\frac{5}{6}\)

\(\Leftrightarrow-\frac{5}{6}x=\frac{5}{6}\)\(\Rightarrow x=-1\)

học toán này chắc vui lắm 

Câu 1 : Trái ngô (bắp)

Câu 2: Gãy tay

Câu 3 : Chó đỏ

Câu 4 :bà đó là bò đá ---> bò đá bả chết, bả bay là bảy ba--> bà ấy chết năm bà ấy 73 tuổi!

Câu 5 : rằm là 15 ---> chết 15 con

Vui chứ.

1 + 3x = -5

3x = -6 

x = -2

          1+3x=-5

\(\Leftrightarrow\)3x    = (-5) - 1

\(\Leftrightarrow\)3x    =  -6

\(\Leftrightarrow\)x      =   (-6) : 3

\(\Leftrightarrow\)x      = -2

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

=> \(x+\frac{1}{4}=0\) hoặc \(x-\frac{3}{7}=0\)

<=> \(x=\frac{-1}{4}\)              \(x=\frac{3}{7}\)

vậy x = \(\frac{-1}{4}\) hoặc x = \(\frac{3}{7}\)

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

\(\Rightarrow\orbr{\begin{cases}x+\frac{1}{4}=0\\x-\frac{3}{7}=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-\frac{1}{4}\\x=\frac{3}{7}\end{cases}}\)

\(7-\frac{3}{4}+\frac{1}{3}-\left(6+\frac{5}{4}-\frac{4}{3}\right)-\left(5-\frac{7}{4}+\frac{5}{3}\right)\)

\(=7-\frac{3}{4}+\frac{1}{3}-6-\frac{5}{4}+\frac{4}{3}-5+\frac{7}{4}-\frac{5}{3}\)

\(=\left(7-6-5\right)-\left(\frac{3}{4}+\frac{5}{4}-\frac{7}{4}\right)+\left(\frac{1}{3}+\frac{4}{3}-\frac{5}{3}\right)\)

\(=-4-\frac{1}{4}=-\frac{17}{4}\)

\(\left(7-\frac{3}{4}+\frac{1}{3}\right)-\left(6+\frac{5}{4}-\frac{4}{3}\right)-\left(5-\frac{7}{4}+\frac{5}{3}\right)\)

\(=7-\frac{3}{4}+\frac{1}{3}-6-\frac{5}{4}+\frac{4}{3}-5+\frac{7}{4}+\frac{5}{3}\)

\(=\left(7-6-5\right)+\left(\frac{-3}{4}-\frac{5}{4}+\frac{7}{4}\right)+\left(\frac{1}{3}+\frac{4}{3}-\frac{5}{3}\right)\)

\(=-4-\frac{1}{4}+0\)

\(=\frac{-17}{4}\)

Học tốt

Bài làm 

\(5x\left(x-\frac{1}{3}\right)=0\Leftrightarrow\orbr{\begin{cases}x=0\\x=\frac{1}{3}\end{cases}}\)

\(5x\left(x-\frac{1}{3}\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}5x=0\\x-\frac{1}{3}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=\frac{1}{3}\end{cases}}\)

vậy x=0 hoặc x=1/3

Gọi các số hữu tỉ cần tìm là a₁,a₂,..a₁₉₉₉

Theo bài ra, ta có:

 \(a_1.a_2=\frac{1}{9}\)

\(a_2.a_3=\frac{1}{9}\)

..

.

.

\(a_{1998}.a_{1999}=\frac{1}{9}\)

\(\hept{\begin{cases}\frac{a_1.a_2}{a_2.a_3}=1\\\frac{a_2.a_3}{a_3.a_4}=1\\\frac{a_{1997}.a_{1998}}{a_{1998}.a_{1999}}=1\end{cases}}\Rightarrow\hept{\begin{cases}\frac{a_1}{a_3}=1\\\frac{a_2}{a_4}=1\\\frac{a_{1997}}{a_{1999}}=1\end{cases}\Rightarrow\hept{\begin{cases}a_1=a_3\\a_2=a_4\\a_{1997}=a_{1999}\end{cases}}}\Rightarrow a_1=a_2=...=a_{1999}=\frac{1}{3}\)

SoanToiLaCuopGui113

-4445 phan 1452

Đặt \(2x^2+7x+3=0\)

\(\Leftrightarrow\left(2x+1\right)\left(x+3\right)=0\Leftrightarrow\orbr{\begin{cases}x=-\frac{1}{2}\\x=-3\end{cases}}\)

= 0 hả bạn ;-;

2x² + 7x + 3 = 0

<=> 2x² + x + 6x + 3 = 0

<=> x( 2x + 1 ) + 3( 2x + 1 ) = 0

<=> ( x + 3 )( 2x + 1 ) = 0

<=> \(\orbr{\begin{cases}x+3=0\\2x+1=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-3\\x=-\frac{1}{2}\end{cases}}\)