Question

Tìm x biết

a, (2x+7)²-(x-3)²=0

b, 3x²-8x+4=0

Answer 1

a)\(\left(2x+7\right)^2-\left(x-3\right)^2=0\)

\(\Leftrightarrow\left(2x+7+x-3\right)\left(2x+7-x+3\right)=0\)

\(\Rightarrow\left\{{}\begin{matrix}3x+4=0\\x+10=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=-\dfrac{4}{3}\\x=-10\end{matrix}\right.\)

b)\(3x^2-8x+4=0\)

\(\Leftrightarrow3x^2-2x-6x+4=0\)

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

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

\(\Rightarrow\left\{{}\begin{matrix}x-2=0\\3x-2=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=2\\x=\dfrac{2}{3}\end{matrix}\right.\)