`a, <=>` \(\left[{}\begin{matrix}x+\dfrac{1}{2}=0\\x-\dfrac{3}{4}=0\end{matrix}\right.\)
`<=>` \(\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=\dfrac{3}{4}\end{matrix}\right.\)
`b, <=> 1/3 x + 2/5 (x+1) = 0`
`<=> 1/3 x + 2/5x + 2/5 = 0`
`<=> 11/15x = -2/5`
`=> x = -2/5 : 11/15`
`=> x = -6/11`
a: =>x+1/2=0 hoặc x-3/4=0
=>x=-1/2 hoặc x=3/4
b: =>1/3x+2/5x+2/5=0
=>11/15x=-2/5
=>x=-6/11
`a)(x+1/2)(x-3/4)=0`
`<=>`\(\left[{}\begin{matrix}x+\dfrac{1}{2}=0\\x-\dfrac{3}{4}=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0-\dfrac{1}{2}\\x=0+\dfrac{3}{4}\end{matrix}\right.\)
`<=>`\(\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=\dfrac{3}{4}\end{matrix}\right.\)
Vậy `x∈{-1/2 ; 3/4}`
`b)1/3x + 2/5 (x+1) =0`
`<=> 1/3x+2/5x+2/5=0`
`<=> x(1/3 +2/5) = 0-2/5`
`<=> 11/15 x = -2/5`
`=> x= -2/5 :11/15 = -6/11`
Vậy `x=-6/11`
