Giải phương trình sau;
\(\frac{2}{x-14}\)-\(\frac{5}{x-13}\)=\(\frac{2}{x-9}\)-\(\frac{5}{x-11}\)
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Ta có: \(\sqrt{16x}=8\)
\(\Leftrightarrow16x=64\)
hay x=4
\(\dfrac{180}{x-4}-\dfrac{180}{x}=\dfrac{1}{2}\)
\(\Leftrightarrow\) \(\dfrac{2x\cdot180}{2x\left(x-4\right)}-\dfrac{2\cdot180\cdot\left(x-4\right)}{2x\left(x-4\right)}=0\)
\(\Leftrightarrow\) \(\dfrac{360x-360x+1440-x^2+4x}{2x\left(x-4\right)}=0\)
\(\Leftrightarrow\) \(\dfrac{-x^2+4x+1440}{2x\left(x-4\right)}=0\)
\(\Leftrightarrow-x^2+4x+1440=0\)
\(\Leftrightarrow-x^2+40x-36x+1440=0\)
\(\Leftrightarrow-x\cdot\left(x-40\right)\cdot\left(-36\right)\cdot\left(x-40\right)=0\)
\(\Leftrightarrow\left(x-40\right)\cdot\left(x-36\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-40=0\\x+36=0\end{matrix}\right.\)
\(x-40=0\)
\(x=0+40\)
\(x=40\)
\(x+36=0\)
\(x=0-36\)
\(x=-36\)
\(\Leftrightarrow\left[{}\begin{matrix}x=40\\x=-36\end{matrix}\right.\)
\(180\left(\dfrac{1}{x-4}-\dfrac{1}{x}\right)=\dfrac{1}{2}\)
\(\dfrac{1}{x-4}-\dfrac{1}{x}=\dfrac{1}{360}\left(đk:x\ne0,4\right)\)
\(\dfrac{x-x+4}{x\left(x-4\right)}=\dfrac{1}{360}\)
\(\dfrac{4}{x\left(x-4\right)}=\dfrac{1}{360}\)
\(x^2-4x=1440\)
\(x^2-4x+4=1444\)
\(\left(x-2\right)^2=1444=38^2\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=38\\x-2=-38\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=40\\x=-36\end{matrix}\right.\)
(12x-1)(6x-1)(4x-1)(3x-1)=5
<=>(12x-1)(12x-2)(12x-3)(12x-4)=40
<=>[(12x-1)(12x-4)] [(12x-2)(12x-3)] =40
<=>(144x^2 - 60x + 4) (144x^2 - 60x + 6) =40
đặt 144x^2 - 60x +4 = t =>144x^2 - 60x +6 = t+2
ta có phương trình:
t ( t+2 ) =40
<=> t^2 + 2t -40 =0
<=> (t+1)^2 -39 =0
<=> t+1=\(\sqrt{39}\) hoặc t+1=\(-\sqrt{39}\) <=> x=\(\sqrt{39}\) -1 hoặc x=\(-\sqrt{39}\) -1
Ta có: \(\dfrac{4}{x^2+2x-3}=\dfrac{2x-5}{x+3}-\dfrac{2x}{x-1}\)
\(\Leftrightarrow\dfrac{\left(2x-5\right)\left(x-1\right)-2x\left(x+3\right)}{\left(x-1\right)\left(x+3\right)}=\dfrac{4}{\left(x+3\right)\left(x-1\right)}\)
Suy ra: \(2x^2-2x-5x+5-2x^2-6x=4\)
\(\Leftrightarrow13x=-1\)
hay \(x=-\dfrac{1}{13}\)
Ta có: \(\sqrt{4x^2-4x+9}=3\)
\(\Leftrightarrow4x^2-4x=0\)
\(\Leftrightarrow4x\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)
\(ĐK:x\ne\pm\dfrac{3}{2}\\ PT\Leftrightarrow2x+3+2x-3=2x+4\\ \Leftrightarrow2x=4\Leftrightarrow x=2\left(tm\right)\)
\(\dfrac{1}{2x-3}+\dfrac{1}{2x+3}=\dfrac{2x+4}{4x^2-9}\)
\(\dfrac{2x+3+2x-3}{\left(2x-3\right)\left(2x+3\right)}=\dfrac{2x+4}{4x^2-9}\)
\(\dfrac{4x}{4x^2-9}=\dfrac{2x+4}{4x^2-9}\Rightarrow4x=2x+4\)
\(\Rightarrow2x=4\Rightarrow x=2\)
\(\sqrt{x^2-x+16}=4\)
\(\Rightarrow x^2-x+16=16\\ \Rightarrow x^2-x=0\\ \Rightarrow x\left(x-1\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=0\\x-1=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)
Ta có: \(\sqrt{x^2-x+16}=4\)
\(\Leftrightarrow x^2-x=0\)
\(\Leftrightarrow x\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)
\(x\left(x-1\right)\left(x+1\right)\left(x+2\right)=24\)
\(\Leftrightarrow\left[x\left(x+1\right)\right]\left[\left(x-1\right)\left(x+2\right)\right]=24\)
\(\Leftrightarrow\left(x^2+x\right)\left(x^2+x-2\right)=24\)
Đặt \(x^2+x-1=a\)
Ta có : \(x^2+x-1=\left(x+\frac{1}{2}\right)^2-\frac{5}{4}\ge-\frac{5}{4}\)
\(\Rightarrow a\ge-\frac{5}{4}\)
Ta có pt : \(\left(a+1\right)\left(a-1\right)=24\)
\(\Leftrightarrow a^2-1=24\)
\(\Leftrightarrow a^2=25\)
\(\Leftrightarrow a=5\left(Do\text{ }a\ge-\frac{5}{4}\right)\)
\(\Leftrightarrow x^2+x-1=5\)
\(\Leftrightarrow x^2+x-6=0\)
\(\Leftrightarrow\left(x-2\right)\left(x+3\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=2\\x=-3\end{cases}}\)