Nghỉ hưu thoi :)) 

Đặt \(x^2=t\left(t\ge0\right)\)

\(\Rightarrow4t^2+7t-2=0\\ \Rightarrow4t^2+8t-t-2=0\\ \Rightarrow4t\left(t+2\right)-\left(t+2\right)=0\\ \Leftrightarrow\left(4t-1\right)\left(t+2\right)=0\\ \Rightarrow\left[{}\begin{matrix}4t-1=0\\t+2=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}t=\dfrac{1}{4}\left(t/m\right)\\t=-2\left(loại\right)\end{matrix}\right.\)

\(\Rightarrow x^2=\dfrac{1}{4}\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=-\dfrac{1}{2}\end{matrix}\right.\)

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

\(=\left(4400+5500\right)+\left(36+64\right)\\ =9900+100\\ =10000\)

Toán đến ddaayy :> 

Ngầu quá đi em yêu ơi :_)