Question

Bài 1:

a) 2/3.x.(x²-4)= 0

b)(x+2)²-(x-2).(x+2)=0

c)x²+2x+1=0

Answer 1

Bài 1:

a) \(\frac{2}{3}.x.\left(x^2-4\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x^2-4=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x^2=2^2\\x^2=\left(-2\right)^2\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-2\end{matrix}\right.\)

Vậy : \(x\in\left\{0,2,-2\right\}\)

b) \(\left(x+2\right)^2-\left(x-2\right).\left(x+2\right)=0\)

\(\Leftrightarrow x^2+4x+4-\left(x^2-2^2\right)=0\)

\(\Leftrightarrow x^2+4x+4-x^2+4=0\)

\(\Leftrightarrow4x+8=0\)

\(\Leftrightarrow4x=-8\)

\(\Leftrightarrow x=-2\)

Vậy : \(x=-2\)

c) \(x^2+2x+1=0\)

\(\Leftrightarrow x^2+2.x.1+1^2=0\)

\(\Leftrightarrow\left(x+1\right)^2=0\)

\(\Leftrightarrow x+1=0\)

\(\Leftrightarrow x=-1\)

Vậy : \(x=-1\)