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b ) 5x + x = 39 - 32
=> 6x = 39 - 9
6x = 30
x = 30 : 6
x = 5
a ) 5x + 3x = 36 : 32 . 4 + 12
=> 8x = 36-2 . 4 + 12
8x = 34 . 4 + 12
8x = 81 . 4 + 12
8x = 324 + 12
8x = 336
x = 336 : 8
x = 42
k nha !
1) 8x = 81 x 4 + 12
8x = 324 + 12
8x = 336
x = 336 : 8
x = 42
2) 6x = 30
x = 30 : 6
x = 5
nha ^^
a: \(4x^3+12=120\)
=>\(4x^3=108\)
=>\(x^3=27=3^3\)
=>x=3
b: \(\left(x-4\right)^2=64\)
=>\(\left[{}\begin{matrix}x-4=8\\x-4=-8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=12\\x=-4\end{matrix}\right.\)
c: (x+1)^3-2=5^2
=>\(\left(x+1\right)^3=25+2=27\)
=>x+1=3
=>x=2
d: 136-(x+5)^2=100
=>(x+5)^2=36
=>\(\left[{}\begin{matrix}x+5=6\\x+5=-6\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=1\\x=-11\end{matrix}\right.\)
e: \(4^x=16\)
=>\(4^x=4^2\)
=>x=2
f: \(7^x\cdot3-147=0\)
=>\(3\cdot7^x=147\)
=>\(7^x=49\)
=>x=2
g: \(2^{x+3}-15=17\)
=>\(2^{x+3}=32\)
=>x+3=5
=>x=2
h: \(5^{2x-4}\cdot4=10^2\)
=>\(5^{2x-4}=\dfrac{100}{4}=25\)
=>2x-4=2
=>2x=6
=>x=3
i: (32-4x)(7-x)=0
=>(4x-32)(x-7)=0
=>4(x-8)*(x-7)=0
=>(x-8)(x-7)=0
=>\(\left[{}\begin{matrix}x-8=0\\x-7=0\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=8\\x=7\end{matrix}\right.\)
k: (8-x)(10-2x)=0
=>(x-8)(x-5)=0
=>\(\left[{}\begin{matrix}x-8=0\\x-5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=8\\x=5\end{matrix}\right.\)
m: \(3^x+3^{x+1}=108\)
=>\(3^x+3^x\cdot3=108\)
=>\(4\cdot3^x=108\)
=>\(3^x=27\)
=>x=3
n: \(5^{x+2}+5^{x+1}=750\)
=>\(5^x\cdot25+5^x\cdot5=750\)
=>\(5^x\cdot30=750\)
=>\(5^x=25\)
=>x=2
a: Ta có: \(142-\left[50-\left(2^3\cdot10-2^3\cdot5\right)\right]\)
\(=142-\left[50-80+40\right]\)
=142-10
=132
a. 142 - [50-(23.10-23.5)]
= 142 - [ 50 - ( 8 . 10 - 8 . 5 )]
= 142 - [ 50 - ( 80 - 40 )]
= 142 - [ 50 - 40 ]
= 142 - 10 = 132
b. 375 : { 32[ 4+(5.32 - 42 )]} - 14
= 375 : { 32[4+(5.9 - 42 )]} - 14
= 375 : { 32[4 + ( 45 - 42 )]} - 14
= 375 : {32[4+3]} - 14
= 375 : 224 - 14
c.{210 : [ 16+3.(6+3.2^2)]} - 3
= {210 : [ 16 + 3.(6+3.4)]} - 3
= { 210 :[16+3.(6+12)]}-3
= {210 : [ 16+3.18)]} - 3
= { 210 : [ 16 + 54]} - 3
= { 210 : 70 } - 3
= 30 - 3 = 27
d.500-{5.[409-(2^3 . 3-21^2)] - 1724}
= 500-{5.[409-(8 . 63 - 21^2] - 1724}
= 500 - { 5.[409- (504 - 441) - 1724}
= 500 -{ 5.[ 409 - 63 ] - 1724}
= 500 - { 5.346 - 1724}
= 500 - { 1720 - 1724 }
= 500 - 6
= 494
2(5x-4)+32=64
=> 2(5x-4)=64-32
=> 2(5x-4)=32
=> 5x-4=32:2
=> 5x-4=16
=> 5x=16+4
=> 5x=20
=> x=20:5
=> x=4
a) Ta có : 2 x : 2 2 = 2 5 nên x = 7.
b) Ta có: 3 x : 3 2 = 3 5 nên x = 7.
c) Ta có : 4 4 : 4 x = 4 2 nên x = 2.
d) Ta có : 5 x : 5 2 = 5 2 nên x = 4,
e) Ta có: 5 x + 1 : 5 = 5 4 nên x = 4.
f) Ta có : 4 2 x - 1 : 4 = 4 2 nên x = 2
1: =>\(5^{x-2}-9=2^4-\left(6^2-6^2\right)\)
=>\(5^{x-2}=16+9=25\)
=>x-2=2
=>x=4
2: \(\Leftrightarrow3^x+16=19^6:19^5-3=19-3=16\)
=>3^x=0
=>x=0
3: \(\Leftrightarrow2^x+2^x\cdot16=272\)
=>2^x*17=272
=>2^x=16
=>x=4
4: \(\Leftrightarrow2^{x-1}+3=24-\left(4^2-2^2+1\right)=24-\left(16-4+1\right)\)
=>\(2^{x-1}+3=24-16+4-1=8+4-1=12-1=11\)
=>2^x-1=8
=>x-1=3
=>x=4
\(5^x+5^{x+1}+5^{x+2}+5^{x+3}=1+2+3+...+87+88-4^2\)
=>\(5^x+5^x\cdot5+5^x\cdot25+5^x\cdot125=88\cdot\dfrac{\left(88+1\right)}{2}-16\)
=>\(156\cdot5^x=44\cdot89-16=3900\)
=>\(5^x=\dfrac{3900}{156}=25\)
=>x=2
\(5.x+x=15:3+13\\ \Rightarrow\left(5+1\right).x=5+13=18\\ \Rightarrow6x=18\\ \Rightarrow x=\dfrac{18}{6}=3\)
\(\dfrac{2}{3}x+\dfrac{1}{3}x+\dfrac{1}{2}=\dfrac{2}{3}\\ \Rightarrow x\left(\dfrac{2}{3}+\dfrac{1}{3}\right)=\dfrac{2}{3}-\dfrac{1}{2}\\ \Rightarrow x=\dfrac{4}{6}-\dfrac{3}{6}=\dfrac{1}{6}\)
\(\dfrac{2}{5}x+x=\dfrac{3}{2}\\ \Rightarrow x\left(\dfrac{2}{5}+1\right)=\dfrac{3}{2}\\ \Rightarrow x\left(\dfrac{2}{5}+\dfrac{5}{5}\right)=\dfrac{3}{2}\\ \Rightarrow x.\dfrac{7}{5}=\dfrac{3}{2}\\ \Rightarrow x=\dfrac{3}{2}:\dfrac{7}{5}\\ \Rightarrow x=\dfrac{3.5}{7.2}=\dfrac{15}{14}\)
\(5\cdot x+x=15:3+13\)
\(\Rightarrow x\cdot\left(5+1\right)=5+13\)
\(\Rightarrow x\cdot6=18\)
\(\Rightarrow x=\dfrac{18}{6}=3\)
================
\(\dfrac{2}{3}\cdot x+\dfrac{1}{3}\cdot x+\dfrac{1}{2}=\dfrac{2}{3}\)
\(\Rightarrow x\cdot\left(\dfrac{2}{3}+\dfrac{1}{3}\right)=\dfrac{2}{3}-\dfrac{1}{2}\)
\(\Rightarrow x\cdot1=\dfrac{1}{6}\)
\(\Rightarrow x=\dfrac{1}{6}\)
=============
\(\dfrac{2}{5}\cdot x+x=\dfrac{3}{2}\)
\(\Rightarrow x\cdot\left(\dfrac{2}{5}+1\right)=\dfrac{3}{2}\)
\(\Rightarrow x\cdot\dfrac{7}{5}=\dfrac{3}{2}\)
\(\Rightarrow x=\dfrac{3}{2}:\dfrac{7}{5}\)
\(\Rightarrow x=\dfrac{15}{14}\)
Lời giải:
$5^x+5^{x+1}+5^{x+2}+5^{x+3}=1+2+3+...+87+88-4^2$
$5^x(1+5+5^2+5^3)=88.89:2-16$
$5^x.156=3900$
$5^x=3900:156=25=5^2$
$\Rightarrow x=2$
2⁵ˣ⁺¹ - 2⁵ˣ = 32
2⁵ˣ.(2 - 1) = 2⁵
2⁵ˣ = 2⁵
5x = 5
x = 5 : 5
x = 1
\(2^{5x+1}-2^{5x}=32\)
\(\Rightarrow2^{5x+1}-2^{5x}=2^5\)
\(\Rightarrow2^{5x}\cdot2-2^{5x}\cdot1=2^5\)
\(\Rightarrow2^{5x}\cdot\left(2-1\right)=2^5\)
\(\Rightarrow2^{5x}\cdot1=2^5\)
\(\Rightarrow2^{5x}=2^5\)
\(\Rightarrow5x=5\)
\(\Rightarrow x=\dfrac{5}{5}\)
\(\Rightarrow x=1\)