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ĐKXĐ: \(x>=-\dfrac{1.96}{3}=-\dfrac{196}{300}=\dfrac{-49}{75}\)
\(\sqrt{\dfrac{1.96+3x}{4}}=\sqrt{0,04}+\dfrac{1}{4}\cdot\sqrt{\dfrac{256}{25}}\)
=>\(\sqrt{\dfrac{3x+1.96}{4}}=0.2+\dfrac{1}{4}\cdot\dfrac{16}{5}=1\)
=>\(\dfrac{3x+1,96}{4}=1\)
=>3x+1,96=4
=>3x=2,04
=>\(x=\dfrac{2.04}{3}=0.68\left(nhận\right)\)
\(\left(\frac{-3}{4}\right)^{3x+5}=\left(\frac{81}{256}\right)^{-1}\)
\(\Rightarrow\left(\frac{-3}{4}\right)^{3x+5}=\frac{256}{81}\)
\(\Rightarrow\left(\frac{-3}{4}\right)^{3x+5}=\left(\frac{-3}{4}\right)^{-4}\)
\(\Rightarrow3x+5=-4\)
\(\Rightarrow3x=-9\)
\(\Rightarrow x=-3\)
Vậy x= -3
a: \(1=4^0\)
\(4=4^1\)
\(16=4^2\)
\(256=4^4\)
b: \(\dfrac{1}{4}=4^{-1}\)
\(\dfrac{1}{64}=4^{-3}\)
\(\dfrac{1}{256}=4^{-4}\)
\(\dfrac{1}{16}=4^{-2}\)
\(\dfrac{1}{1024}=4^{-5}\)
\(\left(\dfrac{-3}{4}\right)^{3x-1}=\dfrac{256}{81}\)
\(\Rightarrow\left(\dfrac{-3}{4}\right)^{3x-1}=\left(\dfrac{4}{3}\right)^4\)
Xem lại đề
-1-1/2-1/4-1/8-1/16-1/32-1/64-1/128-1/256-1/512-1/1024=-1,9990234375
\(a,\left(\dfrac{4}{9}\right)^x=\left(\dfrac{3}{2}\right)^{-5}\\ \Leftrightarrow\left(\dfrac{2}{3}\right)^{2x}=\left(\dfrac{2}{3}\right)^5\\ \Rightarrow x=\dfrac{5}{2}\)
Vậy....
Cách kia hơi lằng nhằng.
Làm lại:
\(\left(-\frac{3}{4}\right)^{3x-1}=\frac{256}{81}=\left(-\frac{3}{4}\right)^{-4}\)
\(\Rightarrow3x-1=-4\)
\(\Rightarrow3x=-3\)
\(\Rightarrow x=-1\)
Ta có : \(\left(-\frac{3}{4}\right)^{-4}=\frac{256}{81}\)
do đó 3x - 1 = -4
=> 3x = -4 + 1 = -3
=> x = -3 : 3 = -1