4x-5+4x=64
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1.
$\sqrt{3x^2}-\sqrt{12}=0$
$\Leftrightarrow \sqrt{3x^2}=\sqrt{12}$
$\Leftrightarrow 3x^2=12$
$\Leftrightarrow x^2=4$
$\Leftrightarrow (x-2)(x+2)=0\Leftrightarrow x=\pm 2$
2.
$\sqrt{(x-3)^2}=9$
$\Leftrightarrow |x-3|=9$
$\Leftrightarrow x-3=9$ hoặc $x-3=-9$
$\Leftrightarrow x=12$ hoặc $x=-6$
a: 3x=81
nên x=27
b: \(5\cdot4^x=80\)
\(\Leftrightarrow4^x=16\)
hay x=2
c: \(2^x=4^5:4^3\)
\(\Leftrightarrow2^x=2^4\)
hay x=4
\(318-5\left(x-64\right)=103\)
\(\Rightarrow5\left(x-64\right)=318-103\)
\(\Rightarrow5\left(x-64\right)=215\)
\(\Rightarrow x-64=43\)
\(\Rightarrow x=43+64\)
\(\Rightarrow x=107\)
_____________
\(4^x\cdot5+216=296\)
\(\Rightarrow4^x\cdot5=296-216\)
\(\Rightarrow4^x\cdot5-80\)
\(\Rightarrow4^x=16\)
\(\Rightarrow4^x=4^2\)
\(\Rightarrow x=2\)
___________
\(376-6^x:3=364\)
\(\Rightarrow6^x:3=376-364\)
\(\Rightarrow6^x:3=12\)
\(\Rightarrow6^x=36\)
\(\Rightarrow6^x=6^2\)
\(\Rightarrow x=2\)
___________
\(\left(4x-1\right)^2=121\)
\(\Rightarrow\left(4x-1\right)^2=11^2\)
\(\Rightarrow\left[{}\begin{matrix}4x-1=11\\4x-1=-11\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}4x=12\\4x=-10\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{5}{2}\end{matrix}\right.\)
a) \(x^2-64=0\)
\(\Leftrightarrow\left(x-8\right)\left(x+8\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)
b) \(4x^2-4x+1=0\)
\(\Leftrightarrow\left(2x-1\right)^2=0\Leftrightarrow2x-1=0\)
\(\Leftrightarrow x=\dfrac{1}{2}\)
c) \(9-6x+x^2=0\)
\(\Leftrightarrow\left(x-3\right)^2=0\)
\(\Leftrightarrow x-3=0\Leftrightarrow x=3\)
a: Ta có: \(x^2-64=0\)
\(\Leftrightarrow\left(x-8\right)\left(x+8\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)
b: Ta có: \(4x^2-4x+1=0\)
\(\Leftrightarrow\left(2x-1\right)^2=0\)
hay \(x=\dfrac{1}{2}\)
c: ta có: \(x^2-6x+9=0\)
\(\Leftrightarrow\left(x-3\right)^2=0\)
hay x=3
\(\left(\dfrac{1}{2}x+5\right)^3=\dfrac{1}{8}x^3+\dfrac{15}{4}x^2+\dfrac{75}{2}x+25\)
\(8x^3+\dfrac{1}{64}=\left(2x+\dfrac{1}{4}\right)\left(4x^2-\dfrac{1}{2}x+\dfrac{1}{16}\right)\)\(\left(4x-\dfrac{1}{2}\right)^3=64x^3-24x^2+3x-\dfrac{1}{8}\)
`64.4^x=168`
`<=>4^x=168/64=21/8`
Vì `x\inNN` nên không tồn tại `x`
Kết luận:.....
(64-4x).3=24
64-4x=24:3
64-4x=8
4x=64-8
4x=56
x=56:4
x=14
vậy x=14
\(4^{x-5}+4^x=64\)
\(\Rightarrow4^{x-5}+4^x=4^3\)
\(\Rightarrow x-5+x=3\)
\(\Rightarrow2x=3+5\)
\(\Rightarrow2x=8\)
\(\Rightarrow x=4\)