Bài 1:Giải phương trình
a)x^3=3x
⇔x^3-3x=0
⇔x(x^2-3)=0
⇔\(\left[ \begin{array}{l}x=0\\x=± \sqrt[2]{3} \end{array} \right.\)
b)5x (x+7)-x=7
⇔5x (x+7)-(x+7)=0
⇔(5x-1)(x+7)=0
⇔\(\left[ \begin{array}{l}5x-1=0\\x+7=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=1/5\\x=-7\end{array} \right.\)
c)(x-5)^2+5=x
⇔(x-5)^2-x+5=0
⇔(x-5)(x-5-1)=0
⇔\(\left[ \begin{array}{l}x-5=0\\x-6=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=5\\x=6\end{array} \right.\)