Tìm x biếta) x÷0,(7)=0,(32):2,(4)
b)0,(17):2,(3)=x:0,(3)
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20 tháng 11 2021
a) \(\Rightarrow\left(x-2\right)\left(x+1\right)=0\Rightarrow\left[{}\begin{matrix}x=2\\x=-1\end{matrix}\right.\)
b) \(\Rightarrow\left(x-3\right)\left(5x-1\right)=0\Rightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{1}{5}\end{matrix}\right.\)
c) \(\Rightarrow\left[{}\begin{matrix}x=-\dfrac{5}{3}\\x=\dfrac{4}{3}\end{matrix}\right.\)
d) \(\Rightarrow\left(x-7\right)\left(3x-2\right)=0\Rightarrow\left[{}\begin{matrix}x=7\\x=\dfrac{2}{3}\end{matrix}\right.\)
N
20 tháng 11 2021
\(a,\Leftrightarrow\left(x-2\right)\left(x+1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-1\end{matrix}\right.\\ b,\Leftrightarrow\left(x-3\right)\left(5x-1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{1}{5}\end{matrix}\right.\\ c,\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{5}{3}\\x=\dfrac{4}{3}\end{matrix}\right.\\ d,\Leftrightarrow\left(x-7\right)\left(3x-2\right)=0\Leftrightarrow\left[{}\begin{matrix}x=7\\x=\dfrac{2}{3}\end{matrix}\right.\)
TH
3
16 tháng 11 2015
a) X : \(\frac{7}{9}=\frac{32}{99}:\left(2+\frac{4}{9}\right)\) => X : \(\frac{7}{9}=\frac{32}{99}:\frac{22}{9}\)=> X : \(\frac{7}{9}=\frac{64}{81}\) => X = \(\frac{64}{81}.\frac{7}{9}=\frac{64}{63}\)
b) \(\frac{17}{99}:\left(2+\frac{3}{9}\right)=X:\frac{3}{9}\)=> \(\frac{17}{99}:\frac{7}{3}=X:\frac{1}{3}\)=> \(\frac{17}{231}=X:\frac{1}{3}\)=> X = \(\frac{17}{231}.\frac{1}{3}=\frac{17}{693}\)
Vậy...
CD
1
AH
Akai Haruma
Giáo viên
31 tháng 10 2023
Lời giải:
a.
$0< x< \frac{1}{4}+\frac{4}{5}$
$\Rightarrow 0< x< \frac{21}{20}$ hay $0< x< 1,05$
$\Rightarrow x=1$
b.
$\frac{4}{7}+\frac{3}{7}< x< \frac{5}{3}+\frac{2}{3}$
$\Rightarrow 1< x< \frac{7}{3}$
$\Rightarrow x=2$
CD
1
YB
1
TT
27 tháng 9 2015
a) x: 7/9 = 32/99 : 22/9
<=>x * 9/7= 32/99 * 9/22
<=>x* 9/7 = 16/121
<=>x=16/121 : 9/7
<=>x=112/1089
b) 17/99 : 7/3= x: 1/3
<=> 17/99 * 3/7 = x*3
<=> 17/231 = 3x
<=>x= 17/231 : 3
<=>x=17/693
H
3
21 tháng 8 2021
b) \(x^3-x^2-x+1=0\Leftrightarrow\left(x-1\right)^2\left(x+1\right)=0\)
\(\Leftrightarrow x-1=0\) hoặc \(x+1=0\)
\(\Leftrightarrow x=1\) hoặc \(x=-1\)
c) \(x^2-6x+8=0\Leftrightarrow\left(x-4\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-4=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=2\end{matrix}\right.\)
21 tháng 8 2021
a) \(x^3+x^2+x+1=0\Leftrightarrow\left(x+1\right)\left(x^2+1\right)=0\Leftrightarrow x+1=0\Leftrightarrow x=-1\)
(do \(x^2+1\ge1>0\))
NN
1
15 tháng 10 2023
a: 78x(x-97)-x+97=0
=>(x-97)(78x-1)=0
=>\(\left[{}\begin{matrix}x=97\\x=\dfrac{1}{78}\end{matrix}\right.\)
b: \(\dfrac{2}{3}x\left(x^2-4\right)=0\)
=>\(x\left(x-2\right)\left(x+2\right)=0\)
=>\(\left[{}\begin{matrix}x=0\\x=2\\x=-2\end{matrix}\right.\)
c: \(\left(x+2\right)^2-\left(x-2\right)\left(x+2\right)=0\)
=>\(x^2+4x+4-x^2+4=0\)
=>4x+8=0
=>x+2=0
=>x=-2
T
15 tháng 10 2023
\(a,78x\left(x-97\right)-x+97=0\)
\(\Leftrightarrow78x\left(x-97\right)-\left(x-97\right)=0\)
\(\Leftrightarrow\left(x-97\right)\left(78x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-97=0\\78x-1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=97\\x=\dfrac{1}{78}\end{matrix}\right.\)
\(b,\dfrac{2}{3}x\left(x^2-4\right)=0\)
\(\Leftrightarrow\dfrac{2}{3}x\left(x-2\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}\dfrac{2}{3}x=0\\x-2=0\\x+2=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-2\end{matrix}\right.\)
\(c,\left(x+2\right)^2-\left(x-2\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left(x+2\right)\left[\left(x+2\right)-\left(x-2\right)\right]=0\)
\(\Leftrightarrow\left(x+2\right)\left(x+2-x+2\right)=0\)
\(\Leftrightarrow\left(x+2\right)\cdot4=0\)
\(\Leftrightarrow x+2=0\)
\(\Leftrightarrow x=-2\)
KK
5 tháng 9 2021
a. (x - 22) - 1 = 0
<=> x - 4 - 1 = 0
<=> x = 5
b. 4 - (x - 2)2 = 0
<=> 22 - (x - 2)2 = 0
<=> (2 - x + 2)(2 + x - 2) = 0
<=> x(4 - x) = 0
<=> \(\left[{}\begin{matrix}x=0\\4-x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\end{matrix}\right.\)
KK
5 tháng 9 2021
d. (3x - 2)2 - (2x + 3)2 = 5(x + 4)(x - 4)
<=> (3x - 2 - 2x - 3)(3x - 2 + 2x + 3) = 5(x2 - 16)
<=> (x - 5)(5x + 1) = 5x2 - 80
<=> 5x2 + x - 25x - 5 = 5x2 - 80
<=> 5x2 - 5x2 + x - 25x = -80 + 5
<=> -24x = -75
<=> x = \(\dfrac{25}{8}\)
a) x÷0,(7)=0,(32):2,(4)
\(x:\frac{7}{9}=\frac{32}{99}:\frac{22}{9}\)
\(x:\frac{7}{9}=\frac{16}{121}\)
\(x=\frac{16}{121}.\frac{7}{9}\)
\(x=\frac{112}{1089}\)
b)0,(17):2,(3)=x:0,(3)
\(\frac{17}{99}:\frac{7}{3}=x:\frac{1}{3}\)
\(\frac{17}{231}=x:\frac{1}{3}\)
x=\(\frac{17}{231}.\frac{1}{3}\)
\(x=\frac{17}{693}\)