a)1/4 - (2x + 1/2)^2 = 0
b)1/2 x + 2/3 x - 1 = - 3 và 1/3
c)(x - 12)/4 = 1/2
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18 tháng 9 2021
a) \(2x^2-2x-x^2+6=0\)
\(\Leftrightarrow x^2-2x+1+5=0\)
\(\Leftrightarrow\left(x-1\right)^2=-5\) ( vô lý)
Vậy không có x thoả mãn \(2x.\left(x-1\right)-x^2+6=0\)
b) \(x^4-2x^2.\left(3+2x^2\right)+3x^2.\left(x^2+1\right)=-3\)
\(\Leftrightarrow x^4-6x^2-4x^4+3x^4+3x^2+3=0\)
\(\Leftrightarrow3-3x^2=0\)
\(\Leftrightarrow3x^2=3\Leftrightarrow x^2=1\) \(\Leftrightarrow x\in\left\{-1;1\right\}\)
Vậy \(x\in\left\{-1;1\right\}\)
c) \(\left(x+1\right).\left(x^2-x+1\right)-2x=x.\left(x-2\right).\left(x+2\right)\)
\(\Leftrightarrow x^3+1-2x-x.\left(x^2-4\right)=0\)
\(\Leftrightarrow x^3+1-2x-x^3+4x=0\)
\(\Leftrightarrow1+2x=0\Leftrightarrow x=\dfrac{-1}{2}\)
Vậy x=\(\dfrac{-1}{2}\)
d) \(\left(x+3\right).\left(x^2-3x+9\right)-x.\left(x-2\right).\left(x+2\right)=15\)
\(\Leftrightarrow x^3+27-x.\left(x^2-4\right)-15=0\)
\(\Leftrightarrow x^3-27-x^3+4x-15=0\)
\(\Leftrightarrow4x-42=0\)
\(\Leftrightarrow x=10,5\)
Vậy x=10,5
10 tháng 2 2022
b: \(\Leftrightarrow\dfrac{-3x^2+36x+12}{3\left(x+4\right)\left(x-1\right)}=\dfrac{36\left(x-1\right)}{3\left(x+4\right)\left(x-1\right)}+\dfrac{12\left(x+4\right)}{3\left(x-1\right)\left(x+4\right)}\)
\(\Leftrightarrow-3x^2+36x+12=36x-36+12x+48\)
\(\Leftrightarrow-3x^2+36x+12-48x-12=0\)
\(\Leftrightarrow3x\left(x+4\right)=0\)
=>x=0(nhận) hoặc x=-4(loại)
5 tháng 2 2022
a: =>2x-1=0 hoặc 3-2x=0
=>x=1/2 hoặc x=3/2
b: \(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+1=0\\x+\dfrac{3}{4}=0\end{matrix}\right.\Leftrightarrow x\in\left\{0;-1;-\dfrac{3}{4}\right\}\)
c: \(\Leftrightarrow\left[{}\begin{matrix}\dfrac{1}{2}-x=0\\\dfrac{3}{4}-\dfrac{1}{2}x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\\dfrac{1}{2}x=\dfrac{3}{4}\end{matrix}\right.\Leftrightarrow x\in\left\{\dfrac{1}{2};\dfrac{3}{2}\right\}\)
d: \(\Leftrightarrow\left(x-1\right)\left(x+1\right)\left(2x-1-x-3\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x+1\right)\left(x-4\right)=0\)
hay \(x\in\left\{1;-1;4\right\}\)
25 tháng 7 2021
a) (x-2)3+6(x+1)2-x3+12=0
\(\Rightarrow\)x3-6x2+12x-8+6(x2+2x+1)-x3+12=0
\(\Rightarrow\)x3-6x2+12x-8+6x2+12x+6-x3+12=0
\(\Rightarrow\)24x+10=0
\(\Rightarrow\)24x=-10
\(\Rightarrow\)x=\(\dfrac{-10}{24}=\dfrac{-5}{12}\)
25 tháng 7 2021
b)(x-5)(x+5)-(x+3)2+3(x-2)2=(x+1)2-(x-4)(x+4)+3x2
\(\Rightarrow\)x2-25-(x2+6x+9)+3(x2-4x+4)=x2+2x+1-(x2-16)+3x2
\(\Rightarrow\)x2-25-x2-6x-9+3x2-12x+12=x2+2x+1-x2+16+3x2
\(\Rightarrow\)3x2-18x-22=3x2+2x+17
\(\Rightarrow\)3x2-18x-22-3x2-2x-17=0
\(\Rightarrow\)-20x-39=0
\(\Rightarrow\)-20x=39
\(\Rightarrow\)x=\(-\dfrac{39}{20}\)
16 tháng 10 2021
\(1,\\ a,\Leftrightarrow x-\dfrac{1}{3}=0\Leftrightarrow x=\dfrac{1}{3}\\ b,\Leftrightarrow\left[{}\begin{matrix}x-4=4\\x-4=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=8\\x=0\end{matrix}\right.\\ c,\Leftrightarrow2x+1=-2\Leftrightarrow x=-\dfrac{3}{2}\\ 2,\\ a,=1\\ b,=\left(\dfrac{13}{4}\right)^2=\dfrac{169}{16}\\ c,=\left(-\dfrac{7}{4}\right)^2=\dfrac{49}{16}\\ d,=\left(\dfrac{3}{7}\right)^{20}:\left(\dfrac{3}{7}\right)^{12}=\left(\dfrac{3}{7}\right)^8=...\\ e,=\left(3\cdot5\cdot\dfrac{2}{3}\right)^2=10^2=100\)
20 tháng 5 2022
a: Đặt |x|=a
Pt trở thành \(3a^2-14a-5=0\)
=>(a-5)(3a+1)=0
=>a=5(nhận) hoặc a=-1/3(loại)
=>x=-5 hoặc x=5
c: \(\left|x+2\right|-2x+1=x^2+2x+3\)
\(\Leftrightarrow\left|x+2\right|=x^2+4x+2\)
\(\Leftrightarrow\left\{{}\begin{matrix}x^2+4x+2>=0\\\left(x^2+4x+2-x-2\right)\left(x^2+4x+2+x+2\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left(x^2+3x\right)\left(x^2+5x+4\right)=0\)
hay \(x\in\left\{0;-3;-1;-4\right\}\)
\(a,\dfrac{1}{4}-\left(2x+\dfrac{1}{2}\right)^2=0\\ \Leftrightarrow\left(2x+\dfrac{1}{2}\right)^2=\dfrac{1}{4}\\ \Leftrightarrow\left[{}\begin{matrix}2x+\dfrac{1}{2}=\dfrac{1}{2}\\2x+\dfrac{1}{2}=-\dfrac{1}{2}\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}2x=\dfrac{1}{2}-\dfrac{1}{2}\\2x=-\dfrac{1}{2}-\dfrac{1}{2}\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}2x=0\\2x=-1\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=-\dfrac{1}{2}\end{matrix}\right.\) \(b,\dfrac{1}{2}x+\dfrac{2}{3}x-1=-3\dfrac{1}{3}\\ \Leftrightarrow x\left(\dfrac{1}{2}+\dfrac{2}{3}\right)=-\dfrac{10}{3}+1\\ \Leftrightarrow\left(\dfrac{3+4}{6}\right)x=\dfrac{-10}{3}+\dfrac{3}{3}\\ \Leftrightarrow\dfrac{7}{6}x=\dfrac{-7}{3}\\ \Leftrightarrow x=\left(-\dfrac{7}{3}\right):\dfrac{7}{6}\\ \Leftrightarrow x=-2\)
Vậy \(x=0;x=-\dfrac{1}{2}\) Vậy \(x=-2\)
\(c,\dfrac{x-12}{4}=\dfrac{1}{2}\\ \Leftrightarrow2.\left(x-12\right)=4\\ \Leftrightarrow2x-24=4\\ \Leftrightarrow2x=24+2\\ \Leftrightarrow2x=26\\ \Leftrightarrow x=26:2=13\)
Vậy \(x=13\)
thanks bn!