Đáp án+Giải thích các bước giải:
`a) (3x-1/3).(2x+7/3)=0`
`<=>`\(\left[ \begin{array}{l}3x-\dfrac{1}{3}=0\\2x+\dfrac{7}{3}=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}3x=\dfrac{1}{3}\\2x=-\dfrac{7}{3}\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=\dfrac{1}{9}\\x=-\dfrac{7}{6}\end{array} \right.\)
Vậy `x∈{1/9; -7/6}`
`b) (3x+1)-25=75`
`<=> 3x+1=75+25`
`<=> 3x+1 = 100`
`<=> 3x = 100 -1`
`<=> 3x = 99`
`<=> x = 99:3`
`<=> x = 33`
Vậy `x=33`
