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$(3x-1)\left(-\dfrac14-5x\right)\left(-\dfrac27x+3\right)=0$

$3x-1=0$ hoặc $-\dfrac14-5x=0$ hoặc $-\dfrac27x+3=0$

$x=\dfrac13$ hoặc $x=-\dfrac1{20}$ hoặc $x=\dfrac{21}{2}$

Vậy $x\in\left{\dfrac13,-\dfrac1{20},\dfrac{21}{2}\right}$.

$\left|\dfrac34x-5\right|-\dfrac23=\left|-\dfrac14\right|$

$\left|\dfrac34x-5\right|-\dfrac23=\dfrac14$

$\left|\dfrac34x-5\right|=\dfrac14+\dfrac23$

$\left|\dfrac34x-5\right|=\dfrac{11}{12}$

$\dfrac34x-5=\dfrac{11}{12}$ hoặc $\dfrac34x-5=-\dfrac{11}{12}$

$\dfrac34x=\dfrac{71}{12}$ hoặc $\dfrac34x=\dfrac{49}{12}$

$x=\dfrac{71}{9}$ hoặc $x=\dfrac{49}{9}$

Vậy $x\in\left{\dfrac{49}{9},\dfrac{71}{9}\right}$.

1) x (x-2016) + 2015 (2016-x) = 0

 x (x-2016) - 2015 (x- 2016) = 0

(x-2015)(x-2016) =0

\(\Rightarrow\orbr{\begin{cases}x-2015=0\\x-2016=0\end{cases}\Rightarrow\orbr{\begin{cases}x=2015\\x=2016\end{cases}}}\)

Vậy x= 2015; 2016

2) -5x (x-15) + (15-x) = 0

-5x (x-15) - (x-15) =0

(-5x -1) (x-15) =0

\(\Rightarrow\orbr{\begin{cases}-5x-1=0\\x-15=0\end{cases}\Rightarrow\orbr{\begin{cases}-5x=1\\x=15\end{cases}\Rightarrow}\orbr{\begin{cases}x=-\frac{1}{5}\\x=15\end{cases}}}\)

Vậy x= -1/5; 15

3) 3x (3x-7) - (7-3x) =0

3x(3x-7) + (3x -7) =0

(3x+1) (3x-7) =0

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

Vậy x= -1/3 ; 7/3

Bài 1: Thực hiện phép tính 

a, (-1/2)^4 - |-2/3| + 2016^0=1/16-2/3+1

                                       =19/48

b, (2/3 - 5/7) (2/7 + 5/21 -1)=-1/21.-10/21

                                       =-11/21

 = 1/9 + (-1/64).64 +1

 = 1/9 -1 + 1 = 1/9

k mk nha