16^2x = 4^5 . 8^x
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ĐKXĐ: x≠-2
Ta có: \(\frac{2}{x+2}-\frac{2x^2+16}{x^3+8}=\frac{5}{x^2-2x+4}\)
\(\Leftrightarrow\frac{2}{x+2}-\frac{2x^2+16}{\left(x+2\right)\left(x^2-2x+4\right)}-\frac{5}{x^2-2x+4}=0\)
\(\Leftrightarrow\frac{2\left(x^2-2x+4\right)}{\left(x+2\right)\left(x^2-2x+4\right)}-\frac{2x^2+16}{\left(x+2\right)\left(x^2-2x+4\right)}-\frac{5\left(x+2\right)}{\left(x^2-2x+4\right)\left(x+2\right)}=0\)
\(\Leftrightarrow2x^2-4x+8-\left(2x^2+16\right)-5\left(x+2\right)=0\)
\(\Leftrightarrow2x^2-4x+8-2x^2-16-5x-10=0\)
\(\Leftrightarrow-9x-18=0\)
\(\Leftrightarrow-9x=18\)
hay x=-2(ktm)
Vậy: x∈∅
20) -5-(x + 3) = 2 - 5x ⇔ -5 - x - 3 = 2 -5x ⇔ 4x = 10 ⇔ x = \(\frac{5}{2}\)
Vậy...
2: \(3x\left(x-4\right)+2x-8=0\)
=>\(3x\left(x-4\right)+2\left(x-4\right)=0\)
=>\(\left(x-4\right)\left(3x+2\right)=0\)
=>\(\left[{}\begin{matrix}x-4=0\\3x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-\dfrac{2}{3}\end{matrix}\right.\)
3: 4x(x-3)+x2-9=0
=>\(4x\left(x-3\right)+\left(x+3\right)\left(x-3\right)=0\)
=>\(\left(x-3\right)\left(4x+x+3\right)=0\)
=>\(\left(x-3\right)\left(5x+3\right)=0\)
=>\(\left[{}\begin{matrix}x-3=0\\5x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{3}{5}\end{matrix}\right.\)
4: \(x\left(x-1\right)-x^2+3x=0\)
=>\(x^2-x-x^2+3x=0\)
=>2x=0
=>x=0
5: \(x\left(2x-1\right)-2x^2+5x=16\)
=>\(2x^2-x-2x^2+5x=16\)
=>4x=16
=>x=4
a) \(\Rightarrow72-20x-36x+84=30x-240-6x-84\)
\(\Rightarrow80x=480\Rightarrow x=6\)
b) \(\Rightarrow15x+25-8x+12=5x+6x+36+1\)
\(\Rightarrow4x=0\Rightarrow x=0\)
c) \(\Rightarrow10x-16-12x+15=12x-16+11\)
\(\Rightarrow14x=4\Rightarrow x=\dfrac{2}{7}\)
Ta có: \(\frac{2}{x+2}-\frac{2x^2+16}{x^3+8}=\frac{5}{x^2-2x+4}\)
⇔\(\frac{2}{x+2}-\frac{2x^2+16}{\left(x+2\right)\left(x^2-2x+4\right)}-\frac{5}{x^2-2x+4}=0\)
⇔\(\frac{2\left(x^2-2x+4\right)}{\left(x+2\right)\left(x^2-2x+4\right)}-\frac{2x^2+16}{\left(x+2\right)\left(x^2-2x+4\right)}-\frac{5\left(x+2\right)}{\left(x+2\right)\left(x^2-2x+4\right)}=0\)
⇔\(2x^2-4x+8-2x^2-16-5\left(x+2\right)=0\)
⇔\(-4x+8-16-5x-10=0\)
⇔-9x-18=0
hay x=-2
Vậy: x=-2
a) ( x + 2 )( x + 3 ) - ( x - 2 )( x + 5 ) = 16
<=> x2 + 5x + 6 - ( x2 + 3x - 10 ) = 16
<=> x2 + 5x + 6 - x2 - 3x + 10 = 16
<=> 2x + 16 = 16
<=> 2x = 0
<=> x = 0
b) 3x( 2x - 4 ) - 2x( 3x + 5 ) = 44
<=> 6x2 - 12x - 6x2 - 10x = 44
<=> -22x = 44
<=> x = -2
c) 2( 5x - 8 - 3 )( 4x - 5 ) = 4( 3x - 4 )
<=> 2( 5x - 11 )( 4x - 5 ) = 4( 3x - 4 )
<=> 2( 20x2 - 69x + 55 ) = 12x - 16
<=> 40x2 - 138x + 110 = 12x - 16
<=> 40x2 - 138x + 110 - 12x + 16 = 0
<=> 40x2 - 150 + 126 = 0 ( chưa học nghiệm vô tỉ nên để vô nghiệm nha :) )
=> Vô nghiệm
\(a,\Leftrightarrow2x^2+10x-2x^2=12\Leftrightarrow x=\dfrac{12}{10}=\dfrac{6}{5}\\ b,\Leftrightarrow\left(5-2x-4\right)\left(5-2x+4\right)=0\\ \Leftrightarrow\left(1-2x\right)\left(9-2x\right)=0\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=\dfrac{9}{2}\end{matrix}\right.\\ c,\Leftrightarrow3x^2-3x^2+6x=36\Leftrightarrow x=6\\ d,\Leftrightarrow2\left(x+5\right)-x\left(x+5\right)=0\\ \Leftrightarrow\left(2-x\right)\left(x+5\right)=0\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-5\end{matrix}\right.\\ e,\Leftrightarrow4x^2-4x+1-4x^2+196=0\\ \Leftrightarrow-4x=-197\Leftrightarrow x=\dfrac{197}{4}\)
\(f,\Leftrightarrow x^2+8x+16-x^2+1=16\Leftrightarrow8x=-1\Leftrightarrow x=-\dfrac{1}{8}\\ g,Sửa:\left(3x+1\right)^2-\left(x+1\right)^2=0\\ \Leftrightarrow\left(3x+1-x-1\right)\left(3x+1+x+1\right)=0\\ \Leftrightarrow2x\left(4x+2\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-\dfrac{1}{2}\end{matrix}\right.\\ h,\Leftrightarrow x^2+8x-x-8=0\\ \Leftrightarrow\left(x+8\right)\left(x-1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-8\end{matrix}\right.\\ i,\Leftrightarrow2x^2-13x+15=0\\ \Leftrightarrow2x^2+2x-15x-15=0\\ \Leftrightarrow\left(x+1\right)\left(2x-15\right)=0\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=\dfrac{15}{2}\end{matrix}\right.\)
162x = 45 . 8x
=> ( 42 ) 2x = 45 . ( 42 )x
=> 44x = 4 2x + 5
=> 4x = 2x + 5
=> 2x = 5
=> x = 2, 5
Vậy x = 2,5
\(16^{2x}=4^5\cdot8^x\)
\(x=-21\frac{677}{1250}\)
Hok tốt! ^-<