-8x X-16+3x X=1x2x3
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1: =>|x-4|+|x+2|=0
=>x-4=0 và x+2=0
=>\(x\in\varnothing\)
2: =>x^2-x-6=3x+5
=>x^2-4x-11=0
=>x^2-4x+4-15=0
=>(x-2)^2-15=0
=>x=căn 15+2 hoặc x=-căn 15+2
3: =>x^2-x=3x+5
=>x^2-4x-5=0
=>(x-5)(x+1)=0
=>x=-1 hoặc x=5
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a, \(\dfrac{x^3+27}{x^2-3x+9}=\dfrac{x+3}{M}\Leftrightarrow\dfrac{\left(x+3\right)\left(x^2-3x+9\right)}{x^2-3x+9}=\dfrac{x+3}{M}\)
\(\Rightarrow M=\dfrac{x+3}{x+3}=1\)
b, \(\dfrac{M}{x+4}=\dfrac{x^2-8x+16}{16-x^2}=\dfrac{\left(x-4\right)^2}{\left(4-x\right)\left(x+4\right)}=\dfrac{4-x}{x+4}\)
\(\Rightarrow M=\dfrac{\left(4-x\right)\left(x+4\right)}{x+4}=4-x\)
c, tương tự
\(\left(x+4\right)\left(3x-1\right)+\left(x^2+8x+16\right)=0\)
\(\Leftrightarrow\hept{\begin{cases}\left(x+4\right)\left(3x-1\right)=0\\x^2+8x+16=0\end{cases}}\)
Xét PT 1 : \(\left(x+4\right)\left(3x-1\right)=0\Leftrightarrow\orbr{\begin{cases}x=-4\\x=\frac{1}{3}\end{cases}}\)
Xét PT 2 : \(x^2+8x+16=0\Leftrightarrow\left(x+4\right)^2=0\Leftrightarrow x=-4\)
= (3x + 1)^2 - (x-4)^2
= (3x+ 1 +x-4) (3x+1-x+4)
= (4x-3) (2x+5)
Bài 1:
a) \(\Rightarrow3x^2+3x-2x^2-4x+x+1=0\)
\(\Rightarrow x^2=-1\left(VLý\right)\Rightarrow S=\varnothing\)
b) \(\Rightarrow\left(x-2020\right)\left(2x-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=2020\\x=\dfrac{1}{2}\end{matrix}\right.\)
c) \(\Rightarrow\left(x-10\right)\left(x+2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=10\\x=-2\end{matrix}\right.\)
d) \(\Rightarrow\left(x+4\right)^2=0\Rightarrow x=-4\)
e) \(\Rightarrow\left(x+6\right)\left(x-7\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=-6\\x=7\end{matrix}\right.\)
f) \(\Rightarrow\left(5x-4\right)\left(5x+4\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{4}{5}\\x=-\dfrac{4}{5}\end{matrix}\right.\)
Bài 2:
a) \(\Rightarrow3x\left(x^2-4\right)=0\Rightarrow3x\left(x-2\right)\left(x+2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-2\end{matrix}\right.\)
b) \(\Rightarrow x\left(x-2\right)+5\left(x-2\right)=0\Rightarrow\left(x-2\right)\left(x+5\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=2\\x=-5\end{matrix}\right.\)
3x( x2 - 8x + 16 ) = 0
\(\Rightarrow\orbr{\begin{cases}3x=0\\x^2-8x+16=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\\left(x-4\right)^2=0\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=0\\x-4=0\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=0\\x=4\end{cases}}.}\)
\(-8\cdot x-16+3\cdot x=1\cdot2\cdot3\)
\(\left(-8\cdot x+3\cdot x\right)-16=6\)
\(-5x=6+16\)
\(-5x=22\)
\(x=-\frac{22}{5}\)