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Ta có:
\(-5x\left(x-15\right)+\left(15-x\right)=0\)
\(\Rightarrow5x\left[-\left(x-15\right)\right]+\left(15-x\right)=0\)
\(\Rightarrow5x\left(15-x\right)+\left(15-x\right)=0\)
\(\Rightarrow\left(5x+1\right)\left(15-x\right)=0\)
\(\Rightarrow\hept{\begin{cases}5x+1=0\\15-x=0\end{cases}}\)
\(\hept{\begin{cases}5x=0-1\\x=15-0\end{cases}}\)
\(\hept{\begin{cases}5x=-1\\x=15\end{cases}}\)
\(\hept{\begin{cases}x=\frac{-1}{5}\\x=15\end{cases}}\)
Vậy \(x\in\left\{-\frac{1}{5},15\right\}\)
\(15x-3-x^2+2x+x^2-13x=7\)
\(\Leftrightarrow4x=10\Leftrightarrow x=\dfrac{5}{2}\)
Ta có:
3(5x - 1) - x(x - 2) + x2 - 13x = 7
→15x - 3 - x2 + 2x + x2 - 13x = 7
→4x - 3 = 7
→4x = 10
→x = \(\dfrac{5}{2}\)
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
\(5x-\dfrac{4}{5}=x+\dfrac{13}{15}\)
\(\Rightarrow5x-x=\dfrac{13}{15}+\dfrac{4}{5}\)
\(\Rightarrow4x=\dfrac{13}{15}+\dfrac{12}{15}\)
\(\Rightarrow4x=\dfrac{25}{15}\)
\(\Rightarrow4x=\dfrac{5}{3}\)
\(\Rightarrow x=\dfrac{5}{3}:4\)
\(\Rightarrow x=\dfrac{5}{12}\)
5x-4/5=x+13/15
<=>5x-x=13/15+4/5
<=>4x=5/3
<=>x=5/12
vậy ...
-5x(x-15)+(15-x)=0
=>-5x(x-15)-(x-15)=0
=>(-5x-1)(x-15)=0
=>x=15 hoặc x=-1/5
Vậy x=15;-1/5
-5x(x-15)+(15-x)=0
-5x(x-15) - (x-15) =0
(-5x -1)(x-15) =0
Th1: -5x-1 = 0
-5x = 1
x= -1/5
Th2: x- 15 =0
x= 15
Vậy x -1/5 và x=15