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`#040911`
\(5^x\cdot5^{x+1}\cdot5^{x+2}=5^9?\)
\(\Rightarrow5^{x+x+1+x+2}=5^9\\ \Rightarrow5^{3x+3}=5^9\\ \Rightarrow3x+3=9\\ \Rightarrow3x=6\\ \Rightarrow x=6\div3\\ \Rightarrow x=2\)
Vậy, `x=2.`
5x . 5x + 1 . 5x + 2 = 59
5x + x + 1 + x + 2 = 59
x + x + 1 + x + 2 = 9
3x + 3 = 9
3x = 9 - 3
x = 6 : 3
x = 2
Vậy x = 2
a. |x - 5| + 5 = x
<=> |x - 5| = x - 5
<=> x - 5\(\ge\)0
<=> x\(\ge\)5
b. |x - 5| - 5 = -x
<=> |x - 5| = -x + 5
<=> |x - 5| = - (x - 5)
<=> x - 5\(\le\)0
<=> x\(\le\)5
c. |5 - x| + 5 = x
<=> |5 - x| = -(5-x)
<=> 5 - x \(\le\)0
<=> x\(\ge\)5
\(a,\dfrac{5}{8}=\dfrac{x}{14}\)
\(\Rightarrow x=\dfrac{5.14}{8}=8,75\)
Vậy \(x=8,75\)
\(b,\dfrac{x}{6}=-\dfrac{1}{3}\)
\(\Rightarrow x=-\dfrac{1.6}{3}=-2\)
Vậy \(x=-2\)
\(c,-\dfrac{3}{5}=\dfrac{x}{10}\)
\(\Rightarrow x=-\dfrac{3.10}{5}=-6\)
Vậy \(x=-6\)
câu d đã có đáp án
( x - 5 )4 = ( x - 5 )6
=> ( x - 5 )6 - ( x - 5 )4 = 0
=> ( x - 5 )4 . [ ( x - 5 )2 - 1 ] = 0
=> ( x - 5 )4 = 0 hoặc ( x - 5 )2 + 1 = 0
TH1 : ( x - 5 )4 = 0 => x - 5 = 0 => x = 5
TH2 : ( x - 5 )2 + 1 = 0
=> ( x - 5 )2 = 1
=> x - 5 = 1 hoặc -1
=> x = 6 hoặc 4
\(5^{x-1}+5^{x-2}+5^{x-3}=775\\ 5^{x-3}.\left(25+5+1\right)=775\\ 5^{x-3}.31=775\\ 5^{x-3}=\dfrac{775}{31}=25=5^2\\ x-3=2\\ x=5\)
(x-42) - 17 = 127
=> x - 42 = 127 + 17 = 144
=> x = 144 + 42 = 186
23(x+1) = 69
=> x + 1 = 69 : 23 = 3
x = 3 - 1 = 2
2x + 5 = 120 : 2 = 60
=> 2x = 60 - 5 = 55
x = 55 : 2 = 27,5
5x - 2 = 613
=> 5x = 613 + 2 = 615
x = 615 : 5 = 123
a)(x-42)-17=127
(x-42)=127+17
(x-42)=144
x=144+42
x=186
b)23(x+1)=69
(x+1)=69:23
(x+1)=3
x=3-1
x=2
c)2.x+5=120:2
2.x+5=60
2.x=60-5
2.x=55
x=55:2
x=27,5
d)5.x-2=613
5.x=613+2
5.x=615
x=615:5
x=123
\(\left|x-5\right|-x=5\)
\(\left|x-5\right|=5+x\)
\(\Rightarrow\left|x-5\right|^2=\left(x+5\right)^2\)
\(x^2-10x+25=x^2+10x+25\)
\(\Leftrightarrow10x+10x=0\)
\(\Leftrightarrow20x=0\)
\(\Leftrightarrow x=0\)
Vậy \(x=0\)
\(|x-5|-x=5\)
\(\Rightarrow|x-5|=x+5\)
\(\Rightarrow x-5=x+5\)hoặc \(x-5=-\left(x+5\right)\)
TH1:\(x-5=x+5\) TH2:\(x-5=-\left(x+5\right)\)
\(x-x=5+5\) \(x-5=-x-5\)
\(\Rightarrow0=10\)(vô lí) \(x+x=-5+5\)
\(2x=0\)
\(\Rightarrow x=0\)
Vậy \(x=0\)
(!!!Chúc học tốt)