=> 5|x + 1|.|x + 1| = 2.90
=> 5.|x + 1|^2 = 180
=> |x + 1|^2 = 36 vì |x + 1| > 0
=> |x + 1| = 6
=> x + 1 = 6 hoặc x + 1 = -6
=> x = 5 hoặc x = -7
vậy_
\(\frac{5.|x+1|}{2}=\frac{90}{|x+1|}\)
\(\Rightarrow5.|x+1|^2=90.2=180\)
\(\Rightarrow|x+1|^2=180:5=36\)
\(\Rightarrow|x+1|^2=6^2\)
\(\Rightarrow\hept{\begin{cases}x+1=6\\x+1=-6\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=5\\x=-7\end{cases}}\)
\(\frac{5\left|x+1\right|}{2}=\frac{90}{\left|x+1\right|}\)
\(\Leftrightarrow5\left|x+1\right|^2=180\)
\(\Leftrightarrow\left|x+1\right|^2=36\)
\(\Leftrightarrow\orbr{\begin{cases}x+1=6\\x+1=-6\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=5\\x=-7\end{cases}}\)
