Mình cần gấp ai làm được mình rất chân thành cảm ơn 

GTNN là gì vậy??

\(B=\left|2x+3,5\right|+\left|2x+\frac{7}{2}\right|\)

\(=\left|3,5-2x\right|+\left|2x+3,5\right|\ge\left|3,5-2x+2x+3,5\right|=7\)

Dấu '' = '' xảy ra khi \(\left(3,5-2x\right)\left(2x+3,5\right)\ge0\)

\(\Rightarrow\orbr{\begin{cases}3,5-2x\ge0;2x+3,5\ge0\\3,5-2x\le0;2x+3,5\le0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}2x\le3,5;2x\ge-3,5\\2x\ge3,5;2x\le-3,5\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x\le1,75;x\ge-1,75\Rightarrow-1,75\le x\le1,75\\x\ge1,75;x\le-1,75\text{(Vô lý)}\end{cases}}\)

Vậy \(MinB=7\Leftrightarrow-1,75\le x\le1,75\)

\(\left|2x-4\right|=\left|5x+3\right|\)

\(\Rightarrow\orbr{\begin{cases}2x-4=5x+3\\2x-4=-5x+3\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}2x-4=5x+3\\2x-5x=-5x-3\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}2x-5x=3+4\\2x+5x=-3+4\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}-3x=7\\7x=1\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=\frac{-7}{3}\\x=\frac{1}{7}\end{cases}}\)

b) \(2\left|x^2-1\right|+\left|xy-2\right|^{200}-4\)

Ta có: \(\hept{\begin{cases}\left|x^2-1\right|\ge0\\\left|xy-2\right|\ge0\end{cases}}\)

\(\Rightarrow2\left|x^2-1\right|+\left|xy-2\right|^{200}-4\ge-4\)

Dấu '' = '' xảy ra khi: \(\hept{\begin{cases}\left|x^2-1\right|=0\\\left|xy-2\right|=0\end{cases}}\Rightarrow\hept{\begin{cases}x=1\\y=2\end{cases}}\)

a) \(\left|x-3\right|+\left|-2y^2+8\right|+3\)

Ta có: \(\hept{\begin{cases}\left|x-3\right|\ge0\forall x\\\left|-2y^2+8\right|\ge0\forall y\end{cases}}\)

\(\Rightarrow\left|x-3\right|+\left|-2y^2-8\right|\ge0x;y\)

\(\Rightarrow\left|x-3\right|+\left|-2y^2+8\right|+3\ge3\)

Dấu '' = '' xảy ra khi: \(\left|x-3\right|=\left|-2y^2+8\right|=0\Rightarrow\hept{\begin{cases}x=3\\y=2\end{cases}}\)