Tìm x :
3^x+1 + 23 = 2.5^2 . 2022^0
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c, \(x\)(\(x\) - 2022) + 4.(2022 - \(x\)) = 0
(\(x\) - 2022).(\(x\) - 4) = 0
\(\left[{}\begin{matrix}x-2022=0\\x+4=0\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=2022\\x=4\end{matrix}\right.\)
Lời giải:
PT $\Leftrightarrow (\frac{x+1}{2022}+1)+(\frac{x+2}{2021}+1)+...+(\frac{x+23}{2000}+1)=0$
$\Leftrightarrow \frac{x+2023}{2022}+\frac{x+2023}{2021}+...+\frac{x+2023}{2000}=0$
$\Leftrightarrow (x+2023)(\frac{1}{2022}+\frac{1}{2021}+...+\frac{1}{2000})=0$
Dễ thấy tổng trong () luôn dương
$\Rightarrow x+2023=0$
$\Leftrightarrow x=-2023$
240-[23+(13+24.3-x)]=132
240-[23+(13+168-x)]=132
240-[23+(181-x)]=132
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x-8:4-(46-23.2+6.3)=0
\(x-8:4-\left(46-23.2+6.3\right)=0\)
\(x-2-\left(46-46+18\right)=0\)
\(x-2-18=0\)
\(x-2=0+18\)
\(x-2=18\)
\(x=18+2\)
\(x=20\)
Ta có: \(y=f\left(x\right)=2x-3\)
\(f\left(x\right)=0\Rightarrow2x-3=0\Rightarrow x=\dfrac{3}{2}\)
\(f\left(x\right)=1\Rightarrow2x-3=1\Rightarrow x=2\)
\(f\left(x\right)=-\dfrac{3}{2}\Rightarrow2x-3=-\dfrac{3}{2}\Rightarrow x=\dfrac{3}{4}\)
\(f\left(x\right)=2022\Rightarrow2x-3=2022\Rightarrow x=\dfrac{2025}{2}\)
\(a,2x^2+y^2+6x-2xy+9=0\\ \Leftrightarrow\left(x^2-2xy+y^2\right)+\left(x^2+6x+9\right)=0\\ \Leftrightarrow\left(x-y\right)^2+\left(x+3\right)^2=0\\ \Leftrightarrow\left\{{}\begin{matrix}x=y\\x=-3\end{matrix}\right.\Leftrightarrow x=y=-3\\ b,A=\left(x-2021\right)^2+\left(x+2022\right)^2=x^2-4042x+2021^2+x^2+4044x+2022^2\\ A=2x^2+2x+2021^2+2022^2\\ A=2\left(x^2+x+\dfrac{1}{4}\right)+2021^2+2022^2-\dfrac{1}{2}\\ A=2\left(x+\dfrac{1}{2}\right)^2+2021^2+2022^2-\dfrac{1}{2}\ge2021^2+2022^2-\dfrac{1}{2}\\ A_{max}=2021^2+2022^2-\dfrac{1}{2}\Leftrightarrow x=-\dfrac{1}{2}\)\(c,P=\left(a+1\right)\left(a+3\right)\left(a+5\right)\left(a+7\right)+16\\ P=\left(a^2+8a+7\right)\left(a^2+8a+15\right)+16\\ P=\left(a^2+8a+11\right)^2-16+16=\left(a^2+8a+11\right)^2\left(Đpcm\right)\)
Lời giải chi tiết:
\(\dfrac{2022}{\left(x+1\right)\left(x-3\right)}< 0\Rightarrow\left(x+1\right)\left(x-3\right)< 0\)
Trường hợp 1: \(\left\{{}\begin{matrix}x+1>0\\x-3< 0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x>-1\\x< 3\end{matrix}\right.\Rightarrow-1< x< 3\)
Trường hợp 2: \(\left\{{}\begin{matrix}x+1< 0\\x-3>0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x< -1\\x>3\end{matrix}\right.\) (Vô lý)
Vậy \(-1< x< 3\).