HOC24
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Chủ đề / Chương
Bài học
\(F=\sqrt{-3x^2-6x+2}\left(Đk:-1-\sqrt{\dfrac{5}{3}}\le x\le\sqrt{\dfrac{5}{3}}-1\right)\)
\(=\sqrt{-\left(3x^2+6x+3\right)+5}\)
\(=\sqrt{-3\left(x+1\right)^2+5}\)
Vì \(-\left(x+1\right)^2\le0\forall x\)
\(\Rightarrow F\le\sqrt{5}\)
\(MaxF=\sqrt{5}\Leftrightarrow x=-1\)
\(y=\sqrt{2}sin\left(x+\dfrac{\text{π}}{4}\right)\)
\(=\sqrt{2}sinx.cos\dfrac{\text{π}}{4}+\sqrt{2}sin\dfrac{\text{π}}{4}.cosx\)
\(=\sqrt{2}sinx.\dfrac{\sqrt{2}}{2}+\sqrt{2}.\dfrac{\sqrt{2}}{2}+cosx\)
\(=sinx+cosx\)
Tập xác định của hàm số là \(D=R\)
\(\forall x\in D\) thì \(-x\in D\)
Ta có: \(f\left(-x\right)=sin\left(-x\right)+cos\left(-x\right)=-sinx+cosx\ne f\left(x\right)\)
Hàm y không chẵn cũng không lẻ
a) \(6=\sqrt[3]{6^3}=\sqrt{216}>\sqrt[3]{208}=2\sqrt[3]{26}\)
b) \(2\sqrt[3]{6}=\sqrt[3]{2^3.6}=\sqrt[3]{48}>\sqrt[3]{47}\)
a) \(\sqrt{2x}=12\left(đk:x\ge0\right)\)
\(2x=144\)
\(x=72\)
b) \(\sqrt{9x^2-6x}+1=10\)\(\left(Đk:x\le0;x\ge\dfrac{2}{3}\right)\)
\(\sqrt{9x^2-6x}=9\)
\(9x^2-6x=81\)
\(\left(3x-1\right)^2=82\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{\sqrt{82}+1}{3}\\x=\dfrac{1-\sqrt{82}}{3}\end{matrix}\right.\)
c) \(x^2\sqrt{5}-\sqrt{125}=0\)
\(x^2\sqrt{5}=5\sqrt{5}\)
\(x^2=5\)
\(\Rightarrow\left[{}\begin{matrix}x=\sqrt{5}\\x=-\sqrt{5}\end{matrix}\right.\)
a) \(3\sqrt[3]{2}=\sqrt[3]{3^3.2}=\sqrt[3]{54}>\sqrt[3]{53}\)
b) \(22=\sqrt[3]{22^3}=\sqrt[3]{10648}>\sqrt[3]{10638}=3\sqrt[3]{394}\)
\(\sqrt[3]{\dfrac{343a^3b^6}{-216}}=\sqrt[3]{\dfrac{\left(7ab^2\right)^3}{-6^3}}=-\dfrac{7ab^2}{6}\)
\(A=\dfrac{10^{2024}+1}{10^{2023}+1}=\dfrac{10\left(10^{2023}+1\right)}{10^{2023}+1}-\dfrac{9}{10^{2023}+1}=1-\dfrac{9}{10^{2023}+1}\)
\(B=\dfrac{10^{2023}+1}{10^{2022}+1}=\dfrac{10\left(10^{2022}+1\right)}{10^{2022}+1}-\dfrac{9}{10^{2022}+1}=1-\dfrac{9}{10^{2022}+1}\)
Vì \(\dfrac{9}{10^{2023}+1}< \dfrac{9}{10^{2022}+1}\)
\(\Rightarrow A>B\)
\(D=2023-8x+2y+4xy-y^2-5x^2\)
\(=-\left(y^2+5x^2-4xy-2y+8x-2023\right)\)
\(=-\left(y^2-2.y.\left(2x+1\right)+\left(2x+1\right)^2-\left(2x+1\right)^2+5x^2+8x-2023\right)\)
\(=-\left[\left(y-2x-1\right)^2-4x^2-4x-1+5x^2+8x-2023\right]\)
\(=-\left[\left(y-2x-1\right)^2+x^2+4x-2024\right]\)
\(=-\left[\left(y-2x-1\right)^2+\left(x+2\right)^2\right]+2028\)
Vì \(-\left[\left(y-2x-1\right)^2+\left(x+2\right)^2\right]\le0\forall x,y\)
\(MaxD=2028\Leftrightarrow\left\{{}\begin{matrix}x=-2\\y=-3\end{matrix}\right.\)
\(\sqrt{2023+2025}=\sqrt{2.2024}\)
\(2\sqrt{2024}=\sqrt{4.2024}\)
\(\sqrt{2.2024}< \sqrt{4.2024}\)
=> \(\sqrt{2023+2025}< 2.\sqrt{2024}\)
a) \(A=x^2+6x+10\)
\(=\left(x+3\right)^2+1=\left(-103+3\right)^2+1=100^2+1=10001\)
b) \(B=x^3+6x^2+12x+12\)
\(=\left(x+2\right)^3+4=\left(8+2\right)^3+4=1004\)