Bài 1:
a) \(\left(m+2\right).3-5=4\)
\(\Leftrightarrow3m+6-5=4\)
\(\Leftrightarrow3m+1=4\)
\(\Leftrightarrow3m=4-1\)
\(\Leftrightarrow3m=3\)
\(\Leftrightarrow m=1\)
Vậy: m = 1
b) \(\left(m-3\right).\left(-2\right)+8=-10\)
\(\Leftrightarrow-2m+6+8=-10\)
\(\Leftrightarrow-2m+14=-10\)
\(\Leftrightarrow-2m=-10-14\)
\(\Leftrightarrow-2m=-24\)
\(\Leftrightarrow m=12\)
Vậy: m = 12
Bài 2:
a) \(\left(x-2\right)^2=9\)
\(\Leftrightarrow\left(x-2\right)^2=3^2\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=3\\x-2=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-1\end{matrix}\right.\)
b) \(\left(x+3\right)^2-0,16=0\)
\(\Leftrightarrow\left(x+3\right)^2=0,16\)
\(\Leftrightarrow\left(x+3\right)^2=\left(0,4\right)^2\)
\(\Leftrightarrow\left[{}\begin{matrix}x+3=0,4\\x+3=-0,4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-2,6\\x=-3,4\end{matrix}\right.\)
c) \(x^3=25x\)
\(\Leftrightarrow x^3-25x=0\)
\(\Leftrightarrow x\left(x^2-25\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x^2-25=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\pm5\end{matrix}\right.\)
