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LD
18 tháng 7 2017
\(3^x+2+3x=810\)
\(3^x+3x=808\)
\(3\left(1^x+x\right)=808\)
\(3\left(1+x\right)=808\)
\(1+x=\frac{808}{3}\)
\(x=\frac{808}{3}-\frac{3}{3}=\frac{805}{3}\)
NC
31 tháng 3 2017
\(3^x+3^{x+2}=810\)
\(\rightarrow3\left(x+x+2\right)=810\)
\(\rightarrow x+x+2\)\(=810:3\)
\(\rightarrow2x+2\) \(=270\)
\(\rightarrow2x\) \(=270-2\)
\(\rightarrow2x\) \(=268\)
\(\rightarrow x\) \(=134\)
Tk cho mk nhé thks nhìu!
CHÚC BẠN HỌC TỐT!
VT
24 tháng 8 2017
=>\(\left(3^2+1\right).3^{x+1}=810\)
=>\(3^{x+1}=81\)
=>\(3^{x+1}=3^4\)
=>x+1=4
=> x=3
24 tháng 8 2017
3x+1 +3x+3=810
<=> 3x.3 +3x.3.3.3=810
<=>3x.(3+3.3.3)=810
<=>3x.30=810
<=>3x=27
<=>x=3
vậy x=3
bạn k cho mình nha :))
S
30 tháng 9 2016
3x+2=369
=>x+2=69
x=69-2
x=67
2x-5=810
2x-5=230
=>x-5=30
x=30+5
x=35
3x+2+3x=810
3x.32+3x=810
3x.(32+1)=810
3x.10=810
3x=810:10
3x=81
3x=34
=>x=4
5x+1-5x=500
5x.5-5x=500
5x.(5-1)=500
5x.4=500
5x=500:4
5x=125
5x=53
=>x=3
30 tháng 9 2016
a) 3x+2 = 369
x + 2 = 69
x = 69 - 2
x = 67
b) 2x-5 = 810
2x-5 = 230
x - 5 = 30
x = 30 + 5
x = 35
c) 3x+2 + 3x = 810
3x . 9 + 3x . 1 = 810
3x . ( 9 + 1 ) = 810
3x . 10 = 810
3x = 810 : 10
3x = 81
3x = 34
=> x = 4
d) 5x+1 - 5x = 500
5x . 5 - 5x . 1 = 500
5x . ( 5 - 1 ) = 500
5x . 4 = 500
5x = 500 : 4
5x = 125
5x = 53
=> x = 3
NT
2
MV
10 tháng 8 2017
e,
\(2^x-15=17\\ 2^x=17+15\\ 2^x=32\\ 2^x=2^5\\ x=5\)
Vậy \(x=5\)
d,
\(\left(x-1\right)^5-\left(x-1\right)^2=0\\ \left(x-1\right)^2\cdot\left[\left(x-1\right)^3-1\right]=0\\ \Rightarrow\left[{}\begin{matrix}\left(x-1\right)^2=0\\\left(x-1\right)^3-1=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x-1=0\\\left(x-1\right)^3=1\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=1\\\left(x-1\right)^3=1^3\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=1\\x-1=1\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)
Vậy \(x=1\) hoặc \(x=2\)
mấy câu còn lại coi lại đề
30 tháng 5 2017
a,
3x + 3 - [7x+4] = 7 + [4x-1]
=> 3x + 3 - x - 4 = 7 + 4x - 1
=> 2x - 1 = 6 + 4x
=> 2x - 4x = 6 + 1
=> -2x = 7
=> x = -7/2
b,
3x+1 + 3x+3 =810
=> 3x+1[1 + 32] = 810
=> 3x+1 = 810 / 10
=> 3x+1 = 81
=> x = 4
c, \(1\frac{1}{2}:\left[\frac{1}{2}-\frac{1}{3}\right]-x=5\)
\(\Rightarrow\frac{3}{2}:\frac{1}{6}-x=5\Leftrightarrow9-x=5\)
\(\Leftrightarrow x=4\)
d,
\(2,4:\left[25\%+\frac{x}{40}\right]-\frac{12}{15}=3\frac{1}{5}\)
\(\Rightarrow\frac{12}{5}:\left[\frac{1}{4}+\frac{x}{40}\right]-\frac{12}{15}=\frac{16}{5}\)
\(\Leftrightarrow\frac{12}{5}:\left[\frac{10}{40}+\frac{x}{40}\right]=\frac{16}{5}+\frac{12}{15}\Leftrightarrow\frac{12}{5}:\left[\frac{10}{40}+\frac{x}{40}\right]=4\)
\(\Rightarrow\frac{10+x}{40}=\frac{12}{5}:4\Leftrightarrow\frac{10+x}{40}=\frac{3}{5}\)
\(\Rightarrow\frac{10+x}{40}=\frac{24}{40}\Leftrightarrow10+x=24\Rightarrow x=14\)
30 tháng 5 2017
a) 3x + 3 - ( x + 4 ) = 7 + ( 4x - 1 )
3x + 3 - x - 4 = 7 + 4x - 1
2x - 1 = 6 + 4x
-2x = 7
\(\Rightarrow\)x = \(\frac{-7}{2}\)
b) 3x+1 + 3x+3 = 810
3x . 3 + 3x . 33 = 810
3x . ( 3 + 33 ) = 810
3x . 30 = 810
3x = 810 : 30
3x = 27
3x = 33
\(\Rightarrow\)x = 3
c) \(1\frac{1}{2}:\left(\frac{1}{2}-\frac{1}{3}\right)-x=5\)
\(\frac{3}{2}:\left(\frac{1}{2}-\frac{1}{3}\right)-x=5\)
\(\frac{3}{2}:\frac{1}{6}-x=5\)
\(9-x=5\)
\(\Rightarrow x=9-5\)
\(\Rightarrow x=4\)
d) 2,4 : ( 25% + \(\frac{x}{40}\)) - \(\frac{12}{15}\)= \(3\frac{1}{5}\)
\(\frac{12}{5}\) : ( \(\frac{1}{4}\)+ \(\frac{x}{40}\)) - \(\frac{12}{15}\)= \(\frac{16}{5}\)
\(\frac{12}{5}:\left(\frac{1}{4}+\frac{x}{40}\right)=\frac{16}{5}+\frac{12}{15}\)
\(\frac{12}{5}:\left(\frac{1}{4}+\frac{x}{40}\right)=4\)
\(\frac{1}{4}+\frac{x}{40}=\frac{12}{5}:4\)
\(\frac{1}{4}+\frac{x}{40}=\frac{3}{5}\)
\(\frac{x}{40}=\frac{3}{5}-\frac{1}{4}\)
\(\frac{x}{40}=\frac{7}{20}\)
\(\Rightarrow\frac{x}{40}=\frac{14}{40}\)
\(\Rightarrow x=14\)
NH
31 tháng 3 2019
a, \(\left(2x-1\right)^2:9=49\)
\(\left(2x-1\right)^2=441\)
\(\Rightarrow\orbr{\begin{cases}2x-1=441\\2x-1=-441\end{cases}\Rightarrow\orbr{\begin{cases}x=221\\x=-220\end{cases}}}\)
b, \(3^x+3^{x+2}=810\)
\(3^x+3^x.3^2=810\)
\(3^x\left(1+3^2\right)=810\)
\(3^x.10=810\)
\(3^x=81=3^4\)
\(\Rightarrow x=4\)
NH
31 tháng 3 2019
\(\hept{\begin{cases}80⋮x\\56⋮x\end{cases}}\Rightarrow x\inƯC\left(80;56\right)\)
\(80=2^4.5\)
\(56=2^3.7\)
\(ƯCLN\left(80;56\right)=2^3=8\)
\(\RightarrowƯC\left(80;56\right)=Ư\left(8\right)=\left\{\pm1;\pm2;\pm4;\pm8\right\}\)
Mà \(x\ge3\)
\(\Rightarrow x\in\left\{4;8\right\}\)
PA
28 tháng 11 2016
\(8-12x+6x^2-x^3\)
\(=\left(2-x\right)^3\)
\(125x^3-75x^2+15x-1\)
\(=\left(5x-1\right)^3\)
\(x^2-xz-9y^2+3yz\)
\(=\left(x-3y\right)\left(x+3y\right)-z\left(x-3y\right)\)
\(=\left(x-3y\right)\left(x+3y-z\right)\)
\(x^3-x^2-5x+125\)
\(=\left(x+5\right)\left(x^2-5x+25\right)-x\left(x+5\right)\)
\(=\left(x+5\right)\left(x^2-5x+25-x\right)\)
\(=\left(x+5\right)\left(x^2-6x+25\right)\)
\(x^3+2x^2-6x-27\)
\(=x^3+5x^2+9x-3x^2-15x-27\)
\(=x\left(x^2+5x+9\right)-3\left(x^2+5x+9\right)\)
\(=\left(x-3\right)\left(x^2+5x+9\right)\)
\(12x^3+4x^2-27x-9\)
\(=4x^2\left(3x+1\right)-9\left(3x+1\right)\)
\(=\left(3x+1\right)\left(4x^2-9\right)\)
\(=\left(3x+1\right)\left(2x-3\right)\left(2x+3\right)\)
\(4x^4+4x^3-x^2-x\)
\(=4x^3\left(x+1\right)-x\left(x+1\right)\)
\(=x\left(x+1\right)\left(4x^2-1\right)\)
\(=x\left(x+1\right)\left(2x-1\right)\left(2x+1\right)\)
3x+2 + 3x = 810
=> 3x . 32 + 3x = 810
=> 3x . (32 + 1) = 810
=> 3x . (9 + 1) = 810
=> 3x . 10 = 810
=> 3x = 810 : 10
=> 3x = 81 = 34
=> x = 4
Vậy x = 4
Ủng hộ mk nha ^_-
3x + 3x+2 = 810
3x.1 + 3x.1 3x.2 = 810
3x . ( 1 + 32 ) = 810
3x . 10 = 810
3x = 810 : 10 = 81
=> X = 4.