Question

tìm x biết:

a) 4x²-(x-3)²=0

b)x²-4+(x+2)²=0

Answer 1

a ,\(4x^2-\left(x-3\right)^2=0\)

\(\Leftrightarrow\left(2x-x+3\right)\left(2x+x-3\right)=0\)

\(\Leftrightarrow\left(x+3\right)\left(3x-3\right)=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}x+3=0\\3x-3=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-3\\3x=3\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=-3\\x=1\end{matrix}\right.\)

Vậy 

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

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

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

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

Vậy ...