Đáp án:
Giải thích các bước giải:
a) `(2x+1)(x-1)=0`
`⇔` \(\left[ \begin{array}{l}2x+1=0\\x-1=0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=-\dfrac{1}{2}\\x=1\end{array} \right.\)
Vậy `S={- 1/2;1}`
b) `(x+2/3)(x-1/2)=0`
`⇔` \(\left[ \begin{array}{l}x+\dfrac{2}{3}=0\\x-\dfrac{1}{2}=0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=-\dfrac{2}{3}\\x=\dfrac{1}{2}\end{array} \right.\)
Vậy `S={- 2/3;1/2}`
c) `(3x-1)(2x-3)(x+5)=0`
`⇔` \(\left[ \begin{array}{l}3x-1=0\\2x-3=0\\x+5=0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=\dfrac{1}{3}\\x=\dfrac{3}{2}\\x=-5\end{array} \right.\)
Vậy `S={1/3;3/2;-5}`
d) `3x-15=2x(x-5)`
`⇔ 3x-15-2x(x-5)=0`
`⇔ 3(x-5)-2x(x-5)=0`
`⇔ (3-2x)(x-5)=0`
`⇔` \(\left[ \begin{array}{l}3-2x=0\\x-5=0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=\dfrac{3}{2}\\x=5\end{array} \right.\)
Vậy `S={3/2;5}`
