7 - 1 = ........
A: 6
B:0
C:5
K
Khách
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CI
1
7 tháng 11 2021
\(x\left(5-6x\right)+\left(2x-1\right)\left(3x+\text{4}\right)=6\\ \Leftrightarrow5x-6x^2+6x^2+8x-3x-4=6\)
\(\Leftrightarrow10x-4=6\)
\(\Leftrightarrow10x=6+4\\ \Leftrightarrow10x=10\\ \Leftrightarrow x=\dfrac{10}{10}\)
\(\Leftrightarrow x=1\)
\(x^2\left(x-2021\right)-x+2021=0\)
\(\Leftrightarrow x^2\left(x-2021\right)-(x-2021)=0\)
\(\Leftrightarrow\left(x-2021\right)\left(x^2-1\right)=0\)
\(\Leftrightarrow\left(x-2021\right)\left(x-1\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2021=0\\x-1=0\\x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2021\\x=1\\x=-1\end{matrix}\right.\)
BN
1
10 tháng 8 2023
a: =>3x=6
=>x=2
b: =>\(\sqrt{2x+1}\left(\sqrt{2x-1}+1\right)=0\)
=>2x+1=0
=>x=-1/2
c: \(\dfrac{\sqrt{x}-1}{\sqrt{x}+3}=\dfrac{\sqrt{x}-2}{\sqrt{x}+1}\)
=>\(\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)=\left(\sqrt{x}+3\right)\left(\sqrt{x}-2\right)\)
=>\(x+\sqrt{x}-6=x-1\)
=>căn x-6=-1
=>căn x=-1+6=5
=>x=25
VC
1
14 tháng 2 2022
a, \(\dfrac{x}{2}+\dfrac{3x}{5}=-\dfrac{3}{2}\Rightarrow5x+6x=-15\Leftrightarrow x=-\dfrac{15}{11}\)
b, TH1 : \(\dfrac{2}{3}x-\dfrac{4}{7}=0\Leftrightarrow x=\dfrac{6}{7}\);TH2 : \(\dfrac{1}{2}-\dfrac{3}{7x}=0\Rightarrow7x-6=0\Leftrightarrow x=\dfrac{6}{7}\)
c, TH1 : \(\dfrac{4}{5}-2x=0\Leftrightarrow x=\dfrac{4}{5}:2=\dfrac{2}{5}\)
TH2 : \(\dfrac{1}{3}+\dfrac{3}{5x}=0\Rightarrow5x+9=0\Leftrightarrow x=-\dfrac{9}{5}\)
LQ
2
11 tháng 10 2021
\(a,\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{1}{5}=0\\\dfrac{8}{5}+2x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{5}\\x=\dfrac{4}{5}\end{matrix}\right.\)
\(b,\dfrac{x-\dfrac{4}{7}}{x+\dfrac{1}{2}}>0\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x-\dfrac{4}{7}>0\\x+\dfrac{1}{2}>0\end{matrix}\right.\\\left\{{}\begin{matrix}x-\dfrac{4}{7}< 0\\x+\dfrac{1}{2}< 0\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x>\dfrac{4}{7}\\x< -\dfrac{1}{2}\end{matrix}\right.\)
\(c,\dfrac{2x-3}{x+\dfrac{7}{4}}< 0\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}2x-3< 0\\x+\dfrac{7}{4}>0\end{matrix}\right.\\\left\{{}\begin{matrix}2x-3>0\\x+\dfrac{7}{4}< 0\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x< \dfrac{3}{2}\\x >-\dfrac{7}{4}\end{matrix}\right.\\\left\{{}\begin{matrix}x>\dfrac{3}{2}\\x< -\dfrac{7}{4}\end{matrix}\right.\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}-\dfrac{7}{4}< x< \dfrac{3}{2}\\x\in\varnothing\end{matrix}\right.\Leftrightarrow-\dfrac{7}{4}< x< \dfrac{3}{2}\)
NA
1
SN
20 tháng 7 2021
a. 2x+\(\dfrac{4}{5}\)=0 hoặc 3x-\(\dfrac{1}{2}\)=0
2x=- 4/5 hoặc 3x=1/2
x=-2/5 hoặc x=\(\dfrac{1}{6}\)
b. x-\(\dfrac{2}{5}\)=0 hoặc x+\(\dfrac{4}{7}\)=0
x=2/5 hoặc x=-\(\dfrac{4}{7}\)
d. x(1+5/8-12/16)=1
\(\dfrac{7}{8}\)x=1=> x=8/7
NA
6 tháng 3 2022
\(a,x=\dfrac{7}{6}-\dfrac{3}{5}\\ x=\dfrac{35}{30}-\dfrac{18}{30}\\ x=\dfrac{17}{30}\\ b,x=\dfrac{4}{9}-\dfrac{1}{3}\\ x=\dfrac{4}{9}-\dfrac{3}{9}\\ x=\dfrac{1}{9}\)
11 tháng 3 2022
a: =>x=-7/6+5/8=-13/24
b: =>x=-14/25-3/4=-131/100
c: \(x=\dfrac{-33}{26}:\dfrac{-9}{13}=\dfrac{33}{26}\cdot\dfrac{13}{9}=\dfrac{11}{3}\cdot\dfrac{1}{2}=\dfrac{11}{6}\)
d: \(x=\dfrac{4}{9}:\dfrac{5}{3}=\dfrac{4}{9}\cdot\dfrac{3}{5}=\dfrac{12}{45}=\dfrac{4}{15}\)
TP
2
TC
7 tháng 5 2022
a)\(y=\dfrac{5}{3}-\left(\dfrac{7}{12}:\dfrac{5}{6}\right)=\dfrac{5}{3}-\dfrac{7}{10}=\dfrac{50}{30}-\dfrac{21}{30}=\dfrac{29}{30}\)
b)\(y=\dfrac{4}{15}:\left[\left(\dfrac{4}{5}+\dfrac{1}{2}\right)\times\dfrac{4}{13}\right]=\dfrac{4}{15}:\left[\left(\dfrac{8}{10}+\dfrac{5}{10}\right)\times\dfrac{4}{13}\right]\)
\(y=\dfrac{4}{15}:\left[\dfrac{13}{10}\times\dfrac{4}{13}\right]=\dfrac{4}{15}:\dfrac{2}{5}=\dfrac{2}{3}\)
LT
2
15 tháng 2 2022
a, đk : x khác -1 ; x khác 2
\(\Rightarrow4x-8=3x+3\Leftrightarrow x=11\left(tm\right)\)
b, đk : x khác 2 ; -2
\(\Rightarrow\left(x+2\right)^2-8x=0\Leftrightarrow\left(x-2\right)^2=0\Leftrightarrow x=2\left(ktm\right)\)
-> vậy pt vô nghiệm
c, đk : x khác 3 ; 0
\(\Rightarrow x-5\left(x-3\right)=3x+7\Leftrightarrow-4x+15=3x+7\Leftrightarrow-7x=-8\Leftrightarrow x=\dfrac{8}{7}\left(tm\right)\)
TD
15 tháng 2 2022
a)Với \(x\ne-1;x\ne2\)
\(\dfrac{4}{x+1}=\dfrac{3}{x-2}\)
<=>4(x-2)=3(x+1)
<=>4x-8=3x+3
<=>x=11(TM)
b)Với\(x\ne\pm2\)
\(\dfrac{x+2}{2x-4}-\dfrac{4x}{x^2-4}=0\)
<=>\(\dfrac{x+2}{2\left(x-2\right)}-\dfrac{4x}{\left(x+2\right)\left(x-2\right)}=0\)
<=>\(\dfrac{\left(x+2\right)^2-8x}{2\left(x+2\right)\left(x-2\right)}=0\)
<=>\(x^2+4x+4-8x=0\left(Vĩx\ne\pm2\right)\)
<=>\(x^2-4x+4=0\)
<=>\(\left(x-2\right)^2=0\)
<=>x-2=0
<=>x=2(Không thỏa mãn)
c)Với \(x\ne3,x\ne0\)
\(\dfrac{1}{x-3}-\dfrac{5}{x}=\dfrac{3x+7}{x\left(x-3\right)}\)
<=>\(\dfrac{x-5\left(x-3\right)}{x\left(x-3\right)}=\dfrac{3x+7}{x\left(x-3\right)}\)
<=>x-5x+15=3x+7(Vì \(x\ne0,x\ne3\))
<=>7x=8
<=>x=\(\dfrac{8}{7}\left(TM\right)\)
13 tháng 1 2022
Bài 2:
a: =>x=0 hoặc x+3=0
=>x=0 hoặc x=-3
b: =>x-2=0 hoặc 5-x=0
=>x=2 hoặc x=5
c: =>x-1=0
hay x=1
mk là B =0
A : 0
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