tìm x :
a, 5^x + 1 = 126
b, 5^x+(5^3)^2=625
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a) \(\left(2x+\frac{3}{5}\right)^2-\frac{9}{25}=0\)
\(\left(2x+\frac{3}{5}\right)^2=\frac{9}{25}\)
\(\left(2x+\frac{3}{5}\right)^2=\left(\frac{3}{5}\right)^2\)
\(=>2x+\frac{3}{5}=\frac{3}{5}\)
\(2x=\frac{3}{5}-\frac{3}{5}\)
\(2x=0\)
\(x=0:2\)
\(x=0\)
b) \(\left(3x-1\right).\left(-\frac{1}{2x}+5\right)=0\)
=> \(\left(3x-1\right)=0\)hoặc \(\left(-\frac{1}{2x}+5\right)=0\)hoặc \(\left(3x-1\right)\)và\(\left(-\frac{1}{2x}+5\right)\)cùng bằng 0.
\(\orbr{\begin{cases}3x-1=0\\-\frac{1}{2x}+5=0\end{cases}}=>\orbr{\begin{cases}3x=1\\-\frac{1}{2x}=-5\end{cases}}=>\orbr{\begin{cases}x\in\varnothing\\2x=\frac{1}{5}\end{cases}}=>x=\frac{1}{5}:2=>x=\frac{1}{10}\)
a) \(3^{x-1}+3x+3^{x+1}=1053\)
\(=3^x:3+3^x+3^x.3=1053\)
\(=3^x.\dfrac{1}{3}+1+3=1053\)
\(=3^x.\dfrac{13}{5}=1053\)
\(=3^x=243\)
\(\Rightarrow x=5\)
Vậy \(x=5\)
a, 5^x . (5^3)^2=625
5^x . 5^6=5^4
5^x=5^4:5^6
5^x=5^-2
=> x=-2
a: =>2x+5=4
=>2x=-1
hay x=-1/2
b: \(\Leftrightarrow\left(3x-4\right)^2\cdot\left[\left(3x-4\right)^2-1\right]=0\)
=>(3x-4)(3x-5)(3x-3)=0
hay \(x\in\left\{1;\dfrac{4}{3};\dfrac{5}{3}\right\}\)
c: \(\Leftrightarrow3^{x+1}=3^{2x}\)
=>2x=x+1
=>x=1
d: \(\Leftrightarrow2^{2x+3}=2^{2x-10}\)
=>2x+3=2x-10
=>0x=-13(vô lý)
a: \(5^{x}\cdot\left(5^3\right)^2=625\)
=>\(5^{x}=\frac{5^4}{5^6}=5^{-2}\)
=>x=-2
b: \(\left(\frac{12}{15}\right)^{x}=\left(\frac53\right)^{-5}-\left(-\frac35\right)^4\)
=>\(\left(\frac45\right)^{x}=\left(\frac35\right)^5-\left(\frac35\right)^4=\left(\frac35\right)^4\cdot\left(\frac35-1\right)=\left(\frac35\right)^4\cdot\frac{-2}{5}=\frac{-2\cdot3^4}{5^5}\)
=>\(x=\log_{0,8}\left(-2\cdot\frac{3^4}{5^5}\right)\)
c: \(\left(-\frac34\right)^{3x-1}=\frac{256}{81}\)
=>\(\left(-\frac34\right)^{3x-1}=\left(-\frac34\right)^{-4}\)
=>3x-1=-4
=>3x=-3
=>x=-1
d: \(172x^2-7^9:98^3=2^{-3}\)
=>\(172x^2=\frac18+\frac{7^9}{7^6\cdot2^3}=\frac18+\frac{7^3}{2^3}=\frac{1+343}{8}=\frac{344}{8}\)
=>\(x^2=\frac{344}{8}:172=\frac{344}{8\cdot172}=\frac28=\frac14\)
=>\(\left[\begin{array}{l}x=\frac12\\ x=-\frac12\end{array}\right.\)
Bài 1:
a: \(\Leftrightarrow3^x\cdot10=810\)
\(\Leftrightarrow3^x=81\)
hay x=4
c: \(\Leftrightarrow5^x\cdot5+5^x\cdot\dfrac{1}{25}=126\)
\(\Leftrightarrow5^x\cdot\dfrac{126}{25}=126\)
\(\Leftrightarrow5^x=25\)
hay x=2
Bài 2:
a: \(27^{11}=3^{33}\)
\(81^8=3^{32}\)
mà 33>32
nên \(27^{11}>81^8\)
c: \(625^5=\left(5^4\right)^5=5^{20}\)
\(125^7=\left(5^3\right)^7=5^{21}\)
mà 20<21
nên \(625^5< 125^7\)
(-3/4)63x-1=(3/4)^3
3x-1=3+1
3x=3=1
x=4;3
x=4/3
Vậy x=4/3
a) \(5^{x}+1=126\)
\(5^{x}=126-1=125\)
\(125=5^3\)
\(5^{x}=5^3\) \(\Rightarrow x=3\)
Kết luận \(x=3\)
Câu b bạn xem lại đề có sai đề bài ko nhé mình tính mãi ko ra
\(a.5^{x}+1=126\)
\(5^{x}=126-1\)
\(5^{x}=125=5^3\)
⇒ x = 3
vậy x = 3
b. \(5^{x}+\left(5^3\right)^2=625\)
\(5^{x}+5^6=5^4\)
\(5^{x}=5^4-5^6\)
\(5^{x}=625-15625=-15000\)
⇒ x thuộc rỗng vì \(5^{x}>0\forall x\in R\)