\(A=\left(x-4\right)^2+1\)

Ta có: \(\left(x-4\right)^2\ge0\Rightarrow\left(x-4\right)^2+1\ge1\Rightarrow A\ge1\)

\(A_{min}=1\Leftrightarrow x=4\)

\(B=\left|3x-2\right|-5\)

Ta có: \(\left|3x-2\right|\ge0\Rightarrow\left|3x-2\right|-5\ge-5\Rightarrow B\ge-5\)

\(B_{min}=-5\Leftrightarrow x=\dfrac{2}{3}\)

\(C=5-\left(2x-1\right)^4\)

Ta có: \(\left(2x-1\right)^4\ge0\forall x\Rightarrow-\left(2x-1\right)^4\le0\forall x\Rightarrow5-\left(2x-1\right)^4\le5\Rightarrow C\le5\)

\(C_{max}=5\Leftrightarrow x=\dfrac{1}{2}\)

\(D=-3\left(x-3\right)^2-\left(y-1\right)^2-2021\)

Ta có: \(\left\{{}\begin{matrix}-3\left(x-3\right)^2\le0\forall x\\-\left(y-1\right)^2\le0\forall y\end{matrix}\right.\Rightarrow-3\left(x-3\right)^2-\left(y-1\right)^2\le0\forall x,y\Rightarrow-3\left(x-3\right)^2-\left(y-1\right)^2-2021\le-2021\Rightarrow D\le-2021\)

\(D_{max}=-2021\Leftrightarrow\left\{{}\begin{matrix}x=3\\y=1\end{matrix}\right.\)

\(E=-\left|x^2-1\right|-\left(x-1\right)^2-y^2-2020\)

\(=-\left|\left(x-1\right)\left(x+1\right)\right|-\left(x-1\right)^2-y^2-2020\)

Ta có: \(\left\{{}\begin{matrix}\left|\left(x-1\right)\left(x+1\right)\right|\ge0\forall x\Rightarrow-\left|\left(x-1\right)\left(x+1\right)\right|\le0\\\left(x-1\right)^2\ge0\forall x\Rightarrow-\left(x-1\right)^2\le0\\y^2\ge0\Rightarrow-y^2\le0\end{matrix}\right.\Rightarrow E\le-2020\)

\(E_{max}=-2020\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=0\end{matrix}\right.\)

=2+200+1/3+1

=203+1/3

=610/3

201900

= ( 4 + 9 + 20 + 28 + 38 + 1) x 2019

= 100                                     x 2019

=                       201900

tính tổng vận tốc hai xe

0,5833333%

\(x:\dfrac{3}{4}\) = \(\dfrac{9}{14}-\dfrac{1}{7}\)

\(x:\dfrac{3}{4}\) = \(\dfrac{1}{2}\)

\(x=\dfrac{1}{2}\) x \(\dfrac{3}{4}\)

\(x=\dfrac{3}{8}\)

\(x\)x \(\dfrac{1}{2}-\dfrac{1}{4}\)=\(\dfrac{2}{3}\)

\(x\) x \(\dfrac{1}{4}\)     =\(\dfrac{2}{3}\)

\(x\)            = \(\dfrac{2}{3}:\dfrac{1}{4}\)

\(x\)             \(\dfrac{8}{3}\)