Đáp án+Giải thích các bước giải:
1)
4x+9=0
⇔x=`(9)/(4)`
Vậy S={`(9)/(4)`}
2)
-5x+6=0
⇔x=`(-6)/(5)`
Vậy S={`(-6)/(5)`}
3)
x-3=0
⇔x=3
Vậy S={3}
4)
2-2x=0
⇔-2x=-2
⇔x=1
Vậy S={1}
5)
3x+1=0
⇔x=`(-1)/(3)`
Vậy S={`(-1)/(3)`}
6)
4x-2=0
⇔4x=2
⇔x=`(1)/(2)`
Vậy S={`(1)/(2)`}
7)
6x-3=0
⇔x=`(1)/(2)`
Vậy S={`(1)/(2)`}
8)
8+4x=0
⇔4x=-8
⇔x=-2
Vậy S={-2}
9)
$x^2$-1=0
⇔$x^2$=1
⇔x=±1
Vậy S={±1}
10)
$x^2$-9=0
⇔$x^2$=9
⇔x=±3
Vậy S={±3}
11)
$x^2$-4=0
⇔$x^2$=4
⇔x=±2
Vậy S={±2}
12)
$x^2$-3=0
⇔$x^2$=3
⇔x=±$\sqrt{3}$
Vậy S={±$\sqrt{3}$}
13)
$x^2$-x=0
⇔x(x-1)=0
⇔\(\left[ \begin{array}{l}x=0\\x-1=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=1\end{array} \right.\)
Vậy S={0,1}
14)
$x^2$-2x=0
⇔x(x-2)=0
⇔\(\left[ \begin{array}{l}x=0\\x-2=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=-2\end{array} \right.\)
Vậy S={0,-2}
15)
$x^2$-4x=0
⇔x(x-4)=0
⇔\(\left[ \begin{array}{l}x=0\\x-4=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=4\end{array} \right.\)
Vậy S={0,4}
16)
$3x^2$+4x=0
⇔x(3x+4)=0
⇔\(\left[ \begin{array}{l}x=0\\3x+4=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=\frac{-4}{3}\end{array} \right.\)
Vậy S={0,`(-4)/(3)`}
