tìm x biết : x^3=1/8*16^x=2^x
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x^3 = 27
x^3 = 3^3
=> x = 3
(2x-1)^3 = 8
(2x-1)^3 = 2^3
2x-1 = 2
2x = 2+1
2x = 3
x = 3:2
=> ko có x phù hợp.
(x-2)^2 = 16
(x-2)^2 = 4^2
x-2 = 4
x = 4+2
x = 6
Chúc bn học tốt!
x^3 = 27
x^3 = 3^3
Vậy x = 3
Đề bài 2 hình như sai bạn ạ
( x - 2 )^2 = 16
( x- 2 )^2 = 4^2
x - 2 = 4
x = 4 + 2
x = 6
Vậy x = 6
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
1: =>x^2+4x-21=0
=>(x+7)(x-3)=0
=>x=3 hoặc x=-7
2: =>(2x-5-4)(2x-5+4)=0
=>(2x-9)(2x-1)=0
=>x=9/2 hoặc x=1/2
3: =>x^3-9x^2+27x-27-x^3+27+9(x^2+2x+1)=15
=>-9x^2+27x+9x^2+18x+9=15
=>18x=15-9-27=-21
=>x=-7/6
6: =>4x^2+4x+1-4x^2-16x-16=9
=>-12x-15=9
=>-12x=24
=>x=-2
7: =>x^2+6x+9-x^2-4x+32=1
=>2x+41=1
=>2x=-40
=>x=-20
![](https://rs.olm.vn/images/avt/0.png?1311)
3) Tìm số tự nhiên x, biết:
a) \(2^x=4\)
\(2^x=2^2\)
\(\Rightarrow x=2\)
___________
b) \(2^x=1\)
\(2^x=2^0\)
\(\Rightarrow x=0\)
___________
c) \(2^x=16\)
\(2^x=2^4\)
\(\Rightarrow x=4\)
___________
d) \(3^x=9\)
\(3^x=3^2\)
\(\Rightarrow x=2\)
___________
e) \(5^x=125\)
\(5^x=5^3\)
\(\Rightarrow x=3\)
___________
f) \(8^x=64\)
\(8^x=8^2\)
\(\Rightarrow x=2\)
___________
h) \(3^{x+1}=3^2\)
\(\rightarrow x+1=2\)
\(x=2-1\)
\(x=1\)
\(\Rightarrow x=1\)
Chúc bạn học tốt
a: 2^x=4
=>2^x=2^2
=>x=2
b: 2^x=1
=>2^x=2^0
=>x=0
c: 2^x=16
=>2^x=2^4
=>x=4
d; 3^x=9
=>3^x=3^2
=>x=2
e: 5^x=125
=>5^x=5^3
=>x=3
f: 8^x=64
=>8^x=8^2
=>x=2
f: 3^x+1=3^2
=>x+1=2
=>x=1
![](https://rs.olm.vn/images/avt/0.png?1311)
1/ `|x|=10<=> x=\pm 10`
2/ `|x-8|=0<=>x-8=0<=>x=8`
3/ `7+|x|=12<=>|x|=5<=>x=\pm 5`
4/ `|x+1|=3`
$\Leftrightarrow\left[\begin{array}{1}x+1=3\\x+1=-3\end{array}\right.\\\Leftrightarrow\left[\begin{array}{1}x=3\\x=-4\end{array}\right.$
5/ `15-x=16-(14-42)`
`<=>15-x=16+28`
`<=>15-x=44`
`<=>x=-29`
6/ `210-(x-12)=168`
`<=>210-x+12=168`
`<=>222-x=168`
`<=>x=54`
![](https://rs.olm.vn/images/avt/0.png?1311)
1: x=3/4-1/2=3/4-2/4=1/4
2: x-1/5=2/11
=>x=2/11+1/5=21/55
3: x-5/6=16/42-8/56
=>x-5/6=8/21-4/28=5/21
=>x=5/21+5/6=15/14
4: x/5=5/6-19/30
=>x/5=25/30-19/30=6/30=1/5
=>x=1
5: =>|x|=1/3+1/4=7/12
=>x=7/12 hoặc x=-7/12
6: x=-1/2+3/4
=>x=3/4-1/2=1/4
11: x-(-6/12)=9/48
=>x+1/2=3/16
=>x=3/16-1/2=-5/16
1)x= 1/4
2)x= 2/11+ 1/5
x= 21/55
3)x - 5/6 = 5/21
x = 5/21+5/6
x = 15/14
4)x/5 = 5/6 + -19/30
x:5 = 1/5
x = 1/5.5
x = 1
5) |x| - 1/4 = 6/18
|x| = 6/18 - 1/4
|x| =7/12
⇒x= 7/12 hoặc -7/12
6)x = -1/2 +3/4
x= 1/4
7) x/15 = 3/5 + -2/3
x:15 = -1/15
x = -1/15. 15
x = -1
8)11/8 + 13/6 = 85/x
85/24 = 85/x
⇒ x = 24
9) x - 7/8 = 13/12
x = 13/12 + 7/8
x = 47/24
10)x - -6/15 = 4/27
x = 4/27 + (-6/15)
x = -34/135
11) -(-6/12)+x = 9/48
x= 9/48 - 6/12
x = -5/16
12) x - 4/6 = 5/25 + -7/15
x -4/6 = -4/15
x = -4/15 + 4/6
x = 2/5
![](https://rs.olm.vn/images/avt/0.png?1311)
Trả lời
\(\left(x+\frac{1}{2}\right)+\left(x+\frac{1}{4}\right)+\left(x+\frac{1}{8}\right)+\left(x+\frac{1}{16}\right)=\frac{23}{16}\)
\(\Leftrightarrow\left(x+x+x+x\right)+\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right)=\frac{23}{16}\)
\(\Leftrightarrow4x+\left(\frac{8}{16}+\frac{4}{16}+\frac{2}{16}+\frac{1}{16}\right)=\frac{23}{16}\)
\(\Leftrightarrow4x+\frac{8+4+2+1}{16}=\frac{23}{16}\)
\(\Leftrightarrow4x+\frac{15}{16}=\frac{23}{16}\)
\(\Leftrightarrow4x=\frac{23}{16}-\frac{15}{16}\)
\(\Leftrightarrow4x=\frac{8}{16}\)
\(\Leftrightarrow4x=\frac{1}{2}\)
\(\Leftrightarrow x=\frac{1}{2}:4\)
\(\Leftrightarrow x=\frac{1}{8}\)
Vậy x=\(\frac{1}{8}\)
\(\left(x+\frac{1}{2}\right)+\left(x+\frac{1}{4}\right)+\left(x+\frac{1}{8}\right)+\left(x+\frac{1}{16}\right)=\frac{23}{16}\)
\(\Leftrightarrow\left(x+x+x+x\right)+\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right)=\frac{23}{16}\)
\(\Leftrightarrow4x+\left(\frac{8+4+2+1}{16}\right)=\frac{23}{16}\)
\(\Leftrightarrow4x+\frac{15}{16}=\frac{23}{16}\)
\(\Leftrightarrow4x=\frac{23}{16}-\frac{15}{16}\)
\(\Leftrightarrow4x=\frac{1}{2}\)
\(\Leftrightarrow x=\frac{1}{2}:4\)
\(\Leftrightarrow x=\frac{1}{8}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
`1-(5 3/8+x-7 5/24):(-16 2/3)=0`
`=>1-(5+3/8+x-7-5/24):(-50/3)=0`
`=>1=(x-2-11/6):(-50/3)`
`=>1=(x-11/6):(-50/3)`
`=>x-11/6=-50/3`
`=>x=-89/6`
Vậy `x=-89/6`
\(1-\left(5\dfrac{3}{8}+x-7\dfrac{5}{24}\right):\left(-16\dfrac{2}{3}\right)=0\)
\(\Leftrightarrow1-\left(\dfrac{43}{8}+x-\dfrac{173}{24}\right):\dfrac{50}{3}=0\)
\(\Leftrightarrow1-\left(\dfrac{129}{24}-\dfrac{173}{24}+x\right).\dfrac{3}{50}=0\)
\(\Leftrightarrow1+\dfrac{11}{6}-x.\dfrac{3}{50}=0\)
\(\Leftrightarrow\dfrac{17}{6}-x.\dfrac{3}{50}=0\)
\(\Leftrightarrow x.\dfrac{3}{50}=\dfrac{17}{6}\)
\(\Leftrightarrow x=\dfrac{425}{9}\)
-Chúc bạn học tốt-