a) \(9x^2-12x+4=0\)
\(\Leftrightarrow\left(3x\right)^2-3x.2.2+2^2=0\)
\(\Leftrightarrow\left(3x-2\right)^2=0\)
\(\Leftrightarrow3x-2=0\)
\(\Leftrightarrow3x=2\)
\(\Leftrightarrow x=\frac{2}{3}\)
Vậy ...
b) \(\left(x-2\right)^2-25=0\)
\(\Leftrightarrow\left(x-2\right)^2=25\)
\(\Leftrightarrow\left(x-2\right)^2=5^2=\left(-5\right)^2\)
\(\Leftrightarrow\orbr{\begin{cases}x-2=5\\x-2=-5\end{cases}\Leftrightarrow\orbr{\begin{cases}x=7\\x=-3\end{cases}}}\)
Vậy ...
c) \(x^3+3x^2+3x+1=0\)
\(\Leftrightarrow\left(x+1\right)^3=0\)
\(\Leftrightarrow x+1=0\)
\(\Leftrightarrow x=-1\)
Vậy ...
a) \(9x^2-12x+4=0\)
\(\left(3x-2\right)^2=0\)
\(3x-2=0\)
\(x=\frac{2}{3}\)
Vậy.....
b) \(\left(x-2\right)^2-5^2=0\)
\(\left(x-2+5\right)\left(x-2-5\right)=0\)
\(\left(x+3\right).\left(x-7\right)=0\)
=> x+3=0 hoặc x-7=0
<=>x=-3 hoặc x=7
Vậy.......
c) \(x^3+3x^2+3x+1=0\)
\(\left(x+1\right)^3=0\)
\(x+1=0\)
\(x=-1\)
Vậy.......
