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\(\left(\frac{2}{5}-3x\right)^2=\frac{9}{25}\)
\(\Rightarrow\left(\frac{2}{5}-3x\right)^2=\left(\frac{3}{5}\right)^2\)
\(\Rightarrow\frac{2}{5}-3x=\frac{3}{5}\)
\(\Rightarrow3x=\frac{-1}{5}\)
\(\Rightarrow x=\frac{-1}{15}\)
(2/5 - 3 x ) ^2 = ( 3 / 5 )^ 2
-> 2/5 - 3x = 3/5
3x= 2/5 - 3/5
3x=-1/5
x= -1/5 : 3
x=-1/15
\(\left(\frac{2}{5}-3x\right)^2=\frac{9}{25}\)
\(\left(\frac{2}{5}-3x\right)^2=\left(\frac{3}{5}\right)^2\)
\(\Leftrightarrow\frac{2}{5}-3x=\frac{3}{5}\)
\(3x=\frac{2}{5}-\frac{3}{5}\)
\(3x=-\frac{1}{5}\)
\(x=-\frac{1}{5}:3\)
\(x=-\frac{1}{15}\)
a/ \(\left(\frac{1}{5}\right)^x=\left(\frac{1}{5^3}\right)^3=\left(\frac{1}{5}\right)^9\Rightarrow x=9\)
b/ \(\left(\frac{3}{5}\right)^x=\left(\frac{3^2}{5^2}\right)^3=\left(\frac{3}{5}\right)^6\Rightarrow x=6\)
c\(2^{3-2x}=\left(2^3\right)^3=2^9\Rightarrow3-2x=9\Rightarrow x=-3\)
d/ \(2^{3x+1}=32^2=\left(2^5\right)^2=2^{10}\Rightarrow3x+1=10\Rightarrow x=3\)
e/ \(3^{6-3x}=81^3=\left(3^4\right)^3=3^{12}\Rightarrow6-3x=12\Rightarrow x=-2\)
\(\left(\frac{1}{5}\right)^x=\left(\frac{1}{125}\right)^3\Leftrightarrow\left(\frac{1}{5}\right)^x=\left[\left(\frac{1}{5}\right)^3\right]^3\Leftrightarrow\left(\frac{1}{5}\right)^x=\left(\frac{1}{5}\right)^9\Leftrightarrow x=9\)
\(\left(\frac{3}{5}\right)^x=\left(\frac{9}{25}\right)^3\Leftrightarrow\left(\frac{3}{5}\right)^x=\left[\left(\frac{3}{5}\right)^2\right]^3\Leftrightarrow\left(\frac{3}{5}\right)^x=\left(\frac{3}{5}\right)^6\Leftrightarrow x=6\)
\(2^{3-2x}=8^3\Leftrightarrow2^{3-2x}=\left(2^3\right)^3\Leftrightarrow2^{3-2x}=2^9\Leftrightarrow3-2x=9\)
\(\Leftrightarrow2x=3-9\Leftrightarrow2x=-6\Leftrightarrow x=\left(-6\right):2\Leftrightarrow x=-3\)
Các phép còn lại làm tương tự bn nha !
\(\left(3x+1\right)^2=25\)
\(\Rightarrow\left(3x+1\right)^2=5^2=\left(-5\right)^2\)
\(\Rightarrow\orbr{\begin{cases}3x+1=5\\3x+1=-5\end{cases}\Rightarrow\orbr{\begin{cases}3x=5-1=4\\3x=-5-1=-6\end{cases}}}\Rightarrow\orbr{\begin{cases}x=\frac{4}{3}\\x=-2\end{cases}}\)
\(\left[x-\frac{1}{2}\right]+\frac{1}{2}=\frac{5}{8}\)
\(\Rightarrow x-0=\frac{5}{8}\)
\(x=\frac{5}{8}\)
\(\left[x+\frac{3}{4}\right]-\frac{1}{3}=0\)
\(x+\frac{3}{4}=0+\frac{1}{3}=\frac{1}{3}\)
\(x=\frac{1}{3}-\frac{3}{4}\)
\(x=\frac{-5}{12}\)
\(b,\left(\sqrt{1\frac{9}{16}-\sqrt{\frac{9}{16}}}\right):5\)
\(=\left(\sqrt{\frac{25}{16}-\frac{3}{4}}\right):5\)
\(=\sqrt{\frac{13}{16}}:5\)
\(=\frac{\sqrt{13}}{4}:5\)
\(=\frac{\sqrt{13}}{20}\)
1) \(\left(x+0,7\right)^3=-27\Leftrightarrow\left(x+0,7\right)^3=\left(-3\right)^3\Leftrightarrow x+0,7=-3\Leftrightarrow x=-3,7\)2) \(\left(2x-1\right)^{10}=49^5\Leftrightarrow\left(2x-1\right)^{10}=\left(7^2\right)^5\)
\(\Leftrightarrow\left(2x-1\right)^{10}=7^{10}\)
\(\Leftrightarrow2x-1=7\Leftrightarrow x=4\)
mấy câu khác tương tự
\(\left(\frac{2}{5}-3x\right)^2=\frac{9}{25}=\left(\frac{\pm3}{5}\right)^2\)
\(\Rightarrow\orbr{\begin{cases}\frac{2}{5}-3x=\frac{3}{5}\\\frac{2}{5}-3x=\frac{-3}{5}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{-1}{15}\\x=\frac{1}{3}\end{cases}}\)
Vậy,............
(2/5–3x)2=9/25
(2/5–3x)2=(3/5)2
==> 2/5–3x=3/5 hoặc 2/5–3x=—3/5
3x=2/5–3/5 hoặc 3x=2/5–(—3)/5
3x=—1/5 hoặc 3x=1
x=—1/5:3 hoặc x=1:3
x=—1/5.1/3 hoặc x=1/3
x=—1/15 hoặc x=1/3