Đáp án:
Giải thích các bước giải:
` a) x+5x^2=0`
`⇒x(x+5)=0`
`⇒`\(\left[ \begin{array}{l}x=0\\x=-5\end{array} \right.\)
`b) 2x(x+135)-x-135=0`
`⇒2x(x+135)-(x+135)=0`
`⇒(2x-1)(x+135)=0`
`⇒`\(\left[ \begin{array}{l}2x-1=0\\x+135=0\end{array} \right.\)
`⇒`\(\left[ \begin{array}{l}x=0,5\\x=-135\end{array} \right.\)
`c) x^3+x=0`
`⇒x(x^2+1)=0`
Do `x^2+1>0∀x⇔x=0`
`d) x+1=(x+1)^2`
`⇒(x+1)^2-(x+1)=0`
`⇒(x+1)(x+1-1)=0`
`⇒`\(\left[ \begin{array}{l}x=-1\\x=0\end{array} \right.\)
