3x + 3/5 = 1/2 + 2x Giúp em với ạ
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a: =>6x-3x^2-5=4-3x^2-2
=>6x-5=2
=>6x=7
=>x=7/6
b: =>20x+5-12x^2-3x=6x^2-10x+3x-5
=>-12x^2+17x+5-6x^2+7x+5=0
=>-18x^2+24x+10=0
=>x=5/3 hoặc x=-1/3
ĐKXĐ: \(-1\le x\le\dfrac{5}{2}\)
\(\Leftrightarrow\sqrt{3x+3}-3+1-\sqrt{5-2x}=x^3-3x^2-10x+24\)
\(\Leftrightarrow\dfrac{3\left(x-2\right)}{\sqrt{3x+3}+3}+\dfrac{2\left(x-2\right)}{1+\sqrt{5-2x}}=\left(x-2\right)\left(x-4\right)\left(x+3\right)\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\\\dfrac{3}{\sqrt{3x+3}+3}+\dfrac{2}{1+\sqrt{5-2x}}=\left(x-4\right)\left(x+3\right)\left(1\right)\end{matrix}\right.\)
Xét (1), ta có:
\(\dfrac{3}{\sqrt{3x+3}+3}+\dfrac{2}{1+\sqrt{5-2x}}>0\)
\(-1\le x\le\dfrac{5}{2}\Rightarrow\left\{{}\begin{matrix}x+3>0\\x-4< 0\end{matrix}\right.\) \(\Rightarrow\left(x+3\right)\left(x-4\right)< 0\)
\(\Rightarrow\left(1\right)\) vô nghiệm hay pt có nghiệm duy nhất \(x=2\)
a) \(6x^2-15x\)
b) \(x^2+5x+4\)
c) \(49-x^2\)
d) \(x^2+4x+4\)
e) \(9-12x+4x^2\)
f) \(x^3-8\)
\(a,=6x^2-15x\\ b,=x^2+5x+4\\ c,=49-x^2\\ d,=x^2+4x+4\\ e,=9-12x+4x^2\\ f,=x^3-8\)
\(\dfrac{1}{2}-3x+\left|x-1\right|=0\\ \Rightarrow3x+\left|x-1\right|=\dfrac{1}{2}-0\\ \Rightarrow3x+\left|x-1\right|=\dfrac{1}{2}\\ \Rightarrow\left|x-1\right|=\dfrac{1}{2}-3x\\ \Rightarrow\left[{}\begin{matrix}x-1=\dfrac{1}{2}-3x\\x-1=-\dfrac{1}{2}+3x\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x+3x=\dfrac{1}{2}+1\\x-3x=-\dfrac{1}{2}+1\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}4x=\dfrac{3}{2}\\2x=\dfrac{1}{2}\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{8}\\x=\dfrac{1}{4}\end{matrix}\right.\)
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\(\dfrac{1}{2}\left|2x-1\right|+\left|2x-1\right|=x+1\\ \Rightarrow\left|2x-1\right|\cdot\left(\dfrac{1}{2}+1\right)=x+1\\ \Rightarrow\left|2x-1\right|\cdot\dfrac{3}{2}=x+1\\ \Rightarrow\left|2x-1\right|=x+1:\dfrac{3}{2}\\ \Rightarrow\left|2x-1\right|=x+\dfrac{2}{3}\\ \Rightarrow\left[{}\begin{matrix}2x-1=x+\dfrac{2}{3}\\2x-1=-x-\dfrac{2}{3}\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}2x-x=\dfrac{2}{3}+1\\2x+x=-\dfrac{2}{3}+1\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{3}\\3x=\dfrac{1}{3}\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{3}\\x=\dfrac{1}{9}\end{matrix}\right.\)
(3x-1)2-5(2x+1)2+(6x-3)(2x+1)=(x-1)2
<=> (3x-1)2+2(3x-1)(2x+1)+(2x+1)2-6(2x+1)2=(x-1)2
<=> (5x)2-6(4x2+4x+1)-(x2-2x+1)=0
<=> -22x-7=0
=> x=-7/22
\(\left(3x-1\right)^2-5\left(2x+1\right)^2+\left(6x-3\right)\left(2x+1\right)=\left(x-1\right)^2\)
\(\Leftrightarrow9x^2-6x+1+\left(2x+1\right)\left[-5\left(2x+1\right)+6x-3\right]=x^2-1\)
\(\Leftrightarrow9x^2-6x+1+\left(2x+1\right)\left[-10x-5+6x-3\right]=x^2-1\)
\(\Leftrightarrow9x^2-6x+1+\left(2x+1\right)\left[-4x-8\right]=x^2-1\)
\(\Leftrightarrow9x^2-6x+1-4x\left(2x+1\right)-8\left(2x+1\right)=x^2-1\)
\(\Leftrightarrow9x^2-6x+1-8x^2-4x-16x-8=x^2-1\)
\(\Leftrightarrow\left(9x^2-8x^2-x^2\right)-\left(4x+6x+16x\right)+\left(1-8\right)=-1\)
\(\Leftrightarrow0-26x-7=-1\)
\(\Leftrightarrow-26x=-1+7\)
\(\Leftrightarrow-26x=6\)
\(\Leftrightarrow x=\frac{-3}{13}\)
x= \(-\dfrac{1}{10}\)
giải kĩ ra nhé:
3x-2x=\(\dfrac{-3}{5}+\dfrac{1}{2}\)
x=\(-\dfrac{1}{10}\)