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HP
19 tháng 9 2021
a. 2x + 70 = 74
<=> 2x = 4
<=> x = 2
b. 120 - \(\dfrac{4x}{2}\) = 80
<=> 120 - 2x = 80
<=> 120 - 80 = 2x
<=> 2x = 40
<=> x = 20
c. (3x + 5)2 = 400
<=> \(|3x+5|=\sqrt{400}\)
<=> \(|3x+5|=20\)
<=> \(\left[{}\begin{matrix}3x+5=20\\3x+5=-20\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{-25}{3}\end{matrix}\right.\)
I
1
Y
27 tháng 1 2023
\(a,\left(x-\dfrac{1}{2}\right):\dfrac{1}{3}+\dfrac{5}{7}=9\dfrac{5}{7}\)
\(\Leftrightarrow\left(x-\dfrac{1}{2}\right).3=\dfrac{68}{7}-\dfrac{5}{7}\)
\(\Leftrightarrow\left(x-\dfrac{1}{2}\right).3=9\)
\(\Leftrightarrow x-\dfrac{1}{3}=3\)
\(\Leftrightarrow x=3+\dfrac{1}{3}\)
\(\Leftrightarrow x=\dfrac{9}{3}+\dfrac{1}{3}\)
\(\Leftrightarrow x=\dfrac{10}{3}\)
\(b,x+30\%x=-1,31\)
\(\Leftrightarrow x+\dfrac{3}{10}.x=-\dfrac{131}{100}\)
\(\Leftrightarrow x.\left(1+\dfrac{3}{10}\right)=-\dfrac{131}{100}\)
\(\Leftrightarrow x.\dfrac{13}{10}=-\dfrac{131}{100}\)
\(\Leftrightarrow x=-\dfrac{131}{100}.\dfrac{10}{13}\)
\(\Leftrightarrow x=-\dfrac{131}{130}\)
\(c,-\dfrac{2}{3}x+\dfrac{1}{5}=\dfrac{1}{10}\)
\(\Leftrightarrow\dfrac{-2}{3}x=\dfrac{1}{10}-\dfrac{1}{5}\)
\(\Leftrightarrow\dfrac{-2}{3}x=\dfrac{1}{10}-\dfrac{2}{10}\)
\(\Leftrightarrow-\dfrac{2}{3}x=-\dfrac{1}{10}\)
\(\Leftrightarrow x=-\dfrac{1}{10}.\left(-\dfrac{3}{2}\right)\)
\(\Leftrightarrow x=\dfrac{3}{20}\)
18 tháng 8 2023
`#040911`
`a)`
`6 \times x - 5 = 613`
`=> 6 \times x = 613 + 5`
`=> 6 \times x = 618`
`=> x = 618 \div 6`
`=> x = 103`
Vậy, `x = 103`
`b)`
`12 \times x + 3 \times x = 30`
`=> x \times (12 + 3) = 30`
`=> x \times 15 = 30`
`=> x = 30 \div 15`
`=> x = 2`
Vậy, `x = 2`
`c)`
`125 - 25 \times (x - 1) = 100`
`=> 25 \times (x - 1) = 125 - 100`
`=> 25 \times (x - 1) = 25`
`=> x - 1 = 25 \div 25`
`=> x - 1 = 1`
`=> x = 1 + 1`
`=> x = 2`
Vậy, `x = 2`
`d)`
`(x - 2) \times (9x - 4) = 0?`
`=>`
TH1: `x - 2 = 0`
`=> x = 0 + 2`
`=> x = 2`
TH2: `9x - 4 = 0`
`=> 9x = 4`
`=> x = 4/9`
Vậy, `x \in {2; 4/9}.`
HQ
Hà Quang Minh
Giáo viên
18 tháng 8 2023
\(a,6x-5=613\\ \Leftrightarrow6x=618\\ \Leftrightarrow x=103\\ b,12x+3x=30\\ \Leftrightarrow15x=30\\ \Leftrightarrow x=2\\ c,125-25\left(x-1\right)=100\\ \Leftrightarrow25\left(x-1\right)=25\\ \Leftrightarrow x-1=1\\ \Leftrightarrow x=2\\ d,\left(x-2\right)\cdot\left(9x-4\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{4}{9}\end{matrix}\right.\)
26 tháng 6 2023
`@` `\text {Ans}`
`\downarrow`
`a)`
\(5\cdot x^3-5=0\)
`=> 5*x^3 = 0+5`
`=> 5*x^3 = 5`
`=> x^3 = 5 \div 5`
`=> x^3 = 1`
`=> x^3 = 1^3`
`=> x=1`
Vậy, `x=1.`
`b)`
\(( x+1)^2 = 16\)
`=> (x+1)^2 = (+-4)^2`
`=>`\(\left[{}\begin{matrix}x+1=4\\x+1=-4\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=4-1\\x=-4-1\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=3\\x=-5\end{matrix}\right.\)
Vậy, `x \in {3; -5}`
`c)`
\(( x+1)^3 = 27\)
`=> (x+1)^3 = 3^3`
`=> x+1=3`
`=> x=3-1`
`=> x=2`
Vậy, `x=2.`
`d)`
\(( x-1)^3 = 343\)
`=> (x-1)^3 = 7^3`
`=> x-1=7`
`=> x=7+1`
`=> x=8`
Vậy, `x=8.`
`e)`
\((2x - 1^3) = 125\) hay đề là `(2x-1)^3 = 125` vậy ạ?
Mình làm cả 2 TH nhé!
`(2x-1^3)=125`
`=> 2x-1=125`
`=> 2x=125+1`
`=> 2x=126`
`=> x=126 \div 2`
`=> x=63`
TH2:
`(2x-1)^3 = 125`
`=> (2x-1)^3 = 5^3`
`=> 2x-1=5`
`=> 2x=5+1`
`=> 2x=6`
`=> x=6 \div 2`
`=> x=3`
Vậy, `x=3.`
TM
26 tháng 6 2023
(a) \(5x^3-5=0\Leftrightarrow5x^3=5\Leftrightarrow x^3=1\Leftrightarrow x=1\)
(b) \(\left(x+1\right)^2=16\Rightarrow\left[{}\begin{matrix}x+1=4\\x+1=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-5\end{matrix}\right.\)
(c) \(\left(x+1\right)^3=27\Leftrightarrow x+1=3\Leftrightarrow x=2\)
(d) \(\left(x-1\right)^3=343\Leftrightarrow x-1=7\Leftrightarrow x=8\)
(e) \(\left(2x-1\right)^3=125\Leftrightarrow2x-1=5\Leftrightarrow2x=6\Leftrightarrow x=3\)
NH
12
2 tháng 8 2018
a, 219 - 7.(x + 1) = 100
7.(x + 1) = 219 - 100
7.(x + 1) = 119
x + 1 = 119 : 7
x + 1 = 17
x = 17 - 1
x = 16
PN
2 tháng 8 2018
a, 219-7(x+1)=100
7(x+1)=219-100
7(x+1)=119
x+1=119/7
x+1=17
x=17-1
x=16
Vậy x=16
b, 20+23(x+3)=52.4
20+8(x+3)=100
8(x+3)=100-20
8(x+3)=80
x+3=80/8
x+3=10
x=10-3
x=7
Vậy x=7
8 tháng 7 2023
a: x=2/3-4/5=10/15-12/15=-2/15
b: 1/2-x=7/12
=>x=1/2-7/12=-1/12
c: =>7/2:x=-7/2
=>x=-1
d: =>1/6x=3/8-5/2=3/8-20/8=-17/8
=>x=-17/8*6=-102/8=-51/4
e: =>1,5x=-1,5
=>x=-1
18 tháng 1
b: \(\dfrac{5}{7}-\dfrac{2}{3}\cdot x=\dfrac{4}{5}\)
=>\(\dfrac{2}{3}x=\dfrac{5}{7}-\dfrac{4}{5}=\dfrac{25-28}{35}=\dfrac{-3}{35}\)
=>\(x=-\dfrac{3}{35}:\dfrac{2}{3}=\dfrac{-3}{35}\cdot\dfrac{3}{2}=-\dfrac{9}{70}\)
c: \(\dfrac{1}{2}x+\dfrac{3}{5}x=-\dfrac{2}{3}\)
=>\(x\left(\dfrac{1}{2}+\dfrac{3}{5}\right)=-\dfrac{2}{3}\)
=>\(x\cdot\dfrac{5+6}{10}=\dfrac{-2}{3}\)
=>\(x\cdot\dfrac{11}{10}=-\dfrac{2}{3}\)
=>\(x=-\dfrac{2}{3}:\dfrac{11}{10}=-\dfrac{2}{3}\cdot\dfrac{10}{11}=\dfrac{-20}{33}\)
d: \(\dfrac{4}{7}\cdot x-x=-\dfrac{9}{14}\)
=>\(\dfrac{-3}{7}\cdot x=\dfrac{-9}{14}\)
=>\(\dfrac{3}{7}\cdot x=\dfrac{9}{14}\)
=>\(x=\dfrac{9}{14}:\dfrac{3}{7}=\dfrac{9}{14}\cdot\dfrac{7}{3}=\dfrac{3}{2}\)
LX
2
AH
Akai Haruma
Giáo viên
21 tháng 12 2022
Lời giải:
Cần bổ sung điều kiện $x$ là số nguyên.
a.
$2x+5\vdots x+1$
$\Rightarrow 2(x+1)+3\vdots x+1$
$\Rightarrow 3\vdots x+1$
$\Rightarrow x+1\in\left\{\pm 1; \pm 3\right\}$
$\Rightarrow x\in\left\{0; -2; 2; -4\right\}$
b.
$-x-5\vdots -x-1$
$\Rightarrow (-x-1)-4\vdots -x-1$
$\Rightarrow 4\vdots -x-1$
$\Rightarrow -x-1\in\left\{\pm 1; \pm 2; \pm 4\right\}$
$\Rightarrow x\in \left\{0; -2; 1; -3; 3; -5\right\}$
21 tháng 12 2022
a: =>2x+2+3 chia hêt cho x+1
=>\(x+1\in\left\{1;-1;3;-3\right\}\)
=>\(x\in\left\{0;-2;2;-4\right\}\)
b: =>x+5 chia hết cho x+1
=>\(x+1\in\left\{1;-1;2;-2;4;-4\right\}\)
=>\(x\in\left\{0;-2;1;-3;3;-5\right\}\)
a) 5 - x = 8
=> x = -3
Vậy x = -3
b) x - ( -2 ) = 16
=> x + 2 = 16
=> x = 14
Vậy x = 14
c) 219 - ( x + 1 ) = 100
=> x + 1 = 119
=> x = 118
Vậy x = 118
a) 5 - x = 8
x = 5 - 8
x = -3
b) x - ( - 2 ) = 16
x + 2 = 16
x = 16 - 2
x = 14
c) 219 - ( x + 1 ) = 100
x + 1 = 219 - 100
x + 1 = 119
x = 119 - 1
x = 118