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a) \(-45:5.\left(-3-2x\right)=3\)
\(-9.\left(-3-2x\right)=3\)
\(-3-2x=\left(3:-9\right)\)
\(-3-2x=\dfrac{-1}{3}\)
\(-2x=-3-\dfrac{1}{3}\)
-2x=\(\dfrac{-10}{3}\)
\(x=\dfrac{-10}{3}:-2\)
\(x=\dfrac{5}{3}\)
b)
3x - 28 = x + 36
<=> 3x - x = 36 + 28
<=> 2x = 64
<=> x = 32
Vậy x = 32
c)
(-12)2.x = 56 + 10.13.x
144.x = 56 + 130.x
144x – 130 x = 56
14x = 56
x = 56: 14
x = 4
Vậy x = 4
![](https://rs.olm.vn/images/avt/0.png?1311)
Vì 56⋮x,70⋮x ➞ x∈ƯC(56;70)
Ta có:
56=23.7
70=2.5.7
ƯCLN(56;70)=2.7=14
ƯC(56;70)=Ư(14)={1;2;7;14}
Vì 56⋮x,70⋮x và 10<x<20
⇔x=14
Tham khảo:
Ta có:
56 = 2³ . 7
70 = 2 . 5 . 7
⇒ ƯCLN ( 56 ; 70 ) = 2. 7 =14
⇒ ƯC ( 56 ; 70 ) = { 1 ; 2 ; 7 ; 14 }
mà 10<x<20
⇒ x = 14
![](https://rs.olm.vn/images/avt/0.png?1311)
\(2\left|x+1\right|=10\)
Th1 :
\(\left|x+1\right|\ge0\Rightarrow x\ge-1\)
\(2\left(x+1\right)=10\)
\(\Rightarrow2x+2=10\)
\(\Rightarrow2x=8\)
\(\Rightarrow x=4\)
Th2 : \(\left|x+1\right|< 0\Rightarrow x< -1\)
\(2\left(-1-x\right)=10\)
\(\Rightarrow-2-2x=10\)
\(\Rightarrow-2x=8\)
\(\Rightarrow x=-4\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(2\left|x+1\right|=10\)
\(\Rightarrow\left|x+1\right|=5\)
\(\Rightarrow\left\{\begin{matrix}x+1=5\\x+1=-5\end{matrix}\right.\Rightarrow\left\{\begin{matrix}x=4\\x=-6\end{matrix}\right.\)
Vậy \(x\in\left\{4;-6\right\}\)
b) \(\left(-12\right)^2.x=56+10.13.x\)
\(\Rightarrow144x-130x=56\)
\(\Rightarrow14x=56\)
\(\Rightarrow x=4\)
Vậy x = 4
![](https://rs.olm.vn/images/avt/0.png?1311)
a ) 2 l x + 1 l = 10
l x + 1 l = 10 : 2
l x + 1 l = 5
=> \(\orbr{\begin{cases}x+1=5\\x+1=-5\end{cases}}\)=> \(\orbr{\begin{cases}x=5-1\\x=-5-1\end{cases}}\)=> \(\orbr{\begin{cases}x=4\\x=-6\end{cases}}\)
Vậy x thuộc { 4 ; - 6 }
a) 2 | x + 1 | = 10
| x + 1 | = 10/2 = 5
suy ra : x + 1 =5
x + 1 =-5
suy ra x = 4
x = -6
Vậy x = 4, -6
câu b mình chưa nghĩ ra
![](https://rs.olm.vn/images/avt/0.png?1311)
(-12)2 . x = 56 + 10 . 13 . x
144x = 56 + 130x
144x - 130x = 56
14x = 56
x = 56 / 14
x = 4
bài làm của mk
cũng giống bài
của Asuka Kurashina
chúc bn học giỏi!
ahjhj
![](https://rs.olm.vn/images/avt/0.png?1311)
\(1,\\ a,\Leftrightarrow4^{5-x}=4^2\Leftrightarrow5-x=2\Leftrightarrow x=3\\ b,\Leftrightarrow\left[{}\begin{matrix}x-1=5\\x-1=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-4\end{matrix}\right.\\ c,\Leftrightarrow2x+1=3\Leftrightarrow x=2\\ 2,\\ a,3^{100}=\left(3^2\right)^{50}=9^{50}\\ b,2^{98}=\left(2^2\right)^{49}=4^{49}< 9^{49}\\ c,5^{30}=5^{29}\cdot5< 6\cdot5^{29}\\ d,3^{30}=\left(3^3\right)^{10}=27^{10}>8^{10}\\ 4,\\ a,\Leftrightarrow5\left(x-10\right)=10\\ \Leftrightarrow x-10=2\Leftrightarrow x=12\\ b,\Leftrightarrow3\left(70-x\right)+5=92\\ \Leftrightarrow3\left(70-x\right)=87\\ \Leftrightarrow70-x=29\\ \Leftrightarrow x=41\\ c,\Leftrightarrow16+x-5=315-230=85\\ \Leftrightarrow x=74\\ d,\Leftrightarrow2^x-5+74=707:\left(16-9\right)=707:7=101\\ \Leftrightarrow2^x=32=2^5\\ \Leftrightarrow x=5\)
Lời giải:
$x=10(6.5+56)=860$
$a=45354:x=45354:860=52,74$