\(A=\left|x^2+x+16\right|+\left|x^2+x-6\right|=\left|x^2+x+16\right|+\left|6-x^2-x\right|\)
\(\ge\left|x^2+x+16+6-x^2-x\right|=22\)
\(\Rightarrow Min_A=22\)
Dấu " = " xảy ra \(\Leftrightarrow\left(x^2+x+16\right)\left(6-x^2-x\right)\ge0\)
Vì \(x^2+x+16>0\) => \(6-x^2-x\ge0\Leftrightarrow x^2+x-6\le0\)
\(\Leftrightarrow\left(x-2\right)\left(x+3\right)\le0\)
\(\Leftrightarrow2\ge x\ge-3\)
tìm max , min của : A = \(\sqrt{\left(x-2\right)\left(6-x\right)}\)
Cho x,y,z>0 /xyz=8.
Tìm min P= \(\dfrac{x^2}{\sqrt{\left(1+x^3\right)\left(1+y^3\right)}}+\dfrac{y^2}{\sqrt{\left(1+y^3\right)\left(1+z^3\right)}}+\dfrac{z^2}{\sqrt{\left(1+z^3\right)\left(1+x^3\right)}}\)
Tìm Max,Min của
A= \(x\left(2018+\sqrt{2020-x^2}\right)\)
Tìm Min của\(\left(1-\frac{1}{x^2}\right)\left(1-\frac{1}{y^2}\right)\)
Biết X+Y=1
G.sử x, y là các số thực thoả mãn: \(\left(x+\sqrt{3+x^2}\right)\left(y+\sqrt{3+y^2}\right)=9\)
Tìm min: \(P=x^2+xy+y^2\)
Với x>4. Tìm Min của P=\(\frac{\left(x+\sqrt{x}\right)\sqrt{x}}{\left(\sqrt{x}-2\right)\left(\sqrt{x}-1\right)}\)
Cho x,y,z > 0 và xyz=8. Tìm Min P = \(\Sigma\dfrac{x^2}{\sqrt{\left(1+x^3\right)+\left(1+y^3\right)}}\)
1. a) Tìm \(n\in N\)*, \(n>2008\) sao cho \(2^{2008}+2^{2012}+2^{2013}+2^{2014}+2^{2016}+2^n\) là số chính phương
b) tìm x,y > 0 thỏa mãn \(x^2+y^2=2\left(x+y\right)\left(\sqrt{x}+\sqrt{y}-2\right)\)
2. a) \(\left\{{}\begin{matrix}a\ge0\\a+b\ge1\end{matrix}\right.\). Min \(A=\frac{8a^2+b}{4a}+b^2\)
b) \(\left\{{}\begin{matrix}a,b\ge0\\\left(a-b\right)^2=a+b+2\end{matrix}\right.\). Cmr: \(\left(1+\frac{a^3}{\left(b+1\right)^3}\right)\left(1+\frac{b^3}{\left(b+1\right)^3}\right)\le9\)
c) \(x,y>0;\left(x+\sqrt{1+x^2}\right)\left(y+\sqrt{1+y^2}\right)=2020\). Min P = x + y
d) \(x,y,z>0;\sqrt{x^2+y^2}+\sqrt{y^2+z^2}+\sqrt{z^2+x^2}=6\). Min \(P=\frac{x^2}{y+z}+\frac{y^2}{z+x}+\frac{z^2}{x+y}\)
e) \(\left\{{}\begin{matrix}x,y,z>0\\x+y+z+4xyz=4\end{matrix}\right.\) Cmr: \(\left(1+xy+\frac{y}{z}\right)\left(1+yz+\frac{z}{x}\right)\left(1+zx+\frac{x}{y}\right)\ge27\)
f) \(\left\{{}\begin{matrix}x,y,z\ge1\\3x^2+4y^2+5z^2=52\end{matrix}\right.\). Min P = x + y + z
g) \(x,y>0\). Min \(P=\frac{2}{\sqrt{\left(2x+y\right)^3+1}-1}+\frac{2}{\sqrt{\left(x+2y\right)^3+1}-1}+\frac{\left(2x+y\right)\left(x+2y\right)}{4}-\frac{8}{3\left(x+y\right)}\)
GHPT
\(\left\{{}\begin{matrix}7\sqrt{16-y^2}+6=x^2+5x\\\left(x+2\right)^2+2\left(y-4\right)^2=9\end{matrix}\right.\)
