Giải phương trình sau:4X2+4x+1=x4
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\(pt\Leftrightarrow\left(16x^2+24x+9\right)\left(2x^2+3x+1\right)=810\)
\(\Leftrightarrow32x^4+48x^3+16x^2+48x^3+72x^2+24x+18x^2+27x+9-810=0\)
\(\Leftrightarrow32x^4+96x^3+106x^2+51x-801=0\)
\(\Leftrightarrow32x^4+96x^3+106x^2+318x-267x-801=0\)
\(\Leftrightarrow\left(x+3\right)\left(32x^3+106x-267\right)=0\)
\(\Leftrightarrow\left(x+3\right)\left(2x-3\right)\left(16x^2+24x+189\right)=0\)
Vì \(16x^2+24x+89=\left(4x+3\right)^2+80\ge80\) nên \(\orbr{\begin{cases}x+3=0\\2x-3=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-3\\x=\frac{3}{2}\end{cases}}\)
Ta có: \(\left(4x+3\right)^2\left(x+1\right)\left(2x+1\right)=810\)
\(\Leftrightarrow\left(16x^2+24x+9\right)\left(2x^2+3x+1\right)=810\)
Đặt \(a=2x^2+3x+1\)
\(\Rightarrow\left(8a+1\right)a=810\)
\(\Leftrightarrow8a^2+a-810=0\)
\(\Leftrightarrow\left(a-10\right)\left(8a+81\right)=0\)
\(\Rightarrow\left(2x^2+3x-9\right)\left(16x^2+24x+189\right)=0\)
\(\Leftrightarrow\left(x+3\right)\left(2x-3\right)\left(16x^2+24x+189\right)=0\)
Lại có: \(16x^2+24x+189=\left(4x+3\right)^2+80>0\)
\(\Rightarrow\orbr{\begin{cases}x+3=0\\2x-3=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=-3\\x=\frac{3}{2}\end{cases}}\)
c) Ta có: \(C=4x^2+y^2-4xy+8x-4y+4\)
\(=\left(2x-y\right)^2+2\cdot\left(2x-y\right)\cdot2+2^2\)
\(=\left(2x-y+2\right)^2\)
\(4x^2-5x-4\sqrt{x-1}-2=0\left(x\ge1\right)\)
\(\Leftrightarrow\left(4x^2-4x+1\right)-\left(x-1+4\sqrt{x-1}+4\right)=0\)
\(\Leftrightarrow\left(2x-1\right)^2-\left(\sqrt{x-1}+2\right)^2=0\)
\(\Leftrightarrow\left(2x-1-\sqrt{x-1}-2\right)\left(2x-1+\sqrt{x-1}+2\right)=0\)
\(\Leftrightarrow\left(2x-\sqrt{x-1}-3\right)\left(2x+\sqrt{x-1}+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{x-1}=2x-3\\\sqrt{x-1}=-\left(2x+1\right)\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\left(tm\right)\\x\in\varnothing\end{matrix}\right.\)
Vậy với x = 2 thì thỏa mãn pt
ĐK: \(-\dfrac{1}{4}\le x\le3\)
\(pt\Leftrightarrow4x+1-6\sqrt{4x+1}+9+3-x-2\sqrt{3-x}+1=0\)
\(\Leftrightarrow\left(\sqrt{4x+1}-3\right)^2+\left(\sqrt{3-x}-1\right)^2=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\sqrt{4x+1}=3\\\sqrt{3-x}=1\end{matrix}\right.\)
\(\Leftrightarrow x=2\left(tm\right)\)
a: \(\dfrac{2x-1}{3}-\dfrac{5x+2}{7}=x+13\)
\(\Leftrightarrow21\left(x+13\right)=7\left(2x-1\right)-3\left(5x+2\right)\)
\(\Leftrightarrow21x+273=14x-7-15x-6=-x-13\)
=>22x=-286
hay x=-13
b: \(\dfrac{2x-3}{3}-\dfrac{x-3}{6}=\dfrac{4x+3}{5}-17\)
\(\Leftrightarrow10\left(2x-3\right)-5\left(x-3\right)=6\left(4x+3\right)-510\)
\(\Leftrightarrow20x-30-5x+15=24x+18-510\)
\(\Leftrightarrow15x-15=24x-492\)
=>-9x=-477
hay x=53
\(\left(x-2\right)\left(4x+5\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x-2=0\\4x+5=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=2\\x=-\frac{5}{4}\end{matrix}\right.\\ \Rightarrow S=\left\{-\frac{5}{4};2\right\}\)
Đặt \(x^2-4x+5=a\)
\(\frac{5}{a}-a+4=0\)
\(\Leftrightarrow-a^2+4a+5=0\Rightarrow\left[{}\begin{matrix}a=-1\\a=5\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x^2-4x+5=-1\\x^2-4x+5=5\end{matrix}\right.\)
ta có : 4x^2+4x+1=x^4
<=> (2x+1)^2=x^4
<=>2x+1=x^2
<=>x^2-2x-1=0
<=>x^2-2x+1=2
<=>(x-1)^2=2
<=>x-1=căn2
<=>x=1+căn 2
ta có : 4x^2+4x+1=x^4
<=> (2x+1)^2=x^4
<=>2x+1=x^2
<=>x^2-2x-1=0
<=>x^2-2x+1=2
<=>(x-1)^2=2
<=>x-1=căn2
<=>x=1+căn 2