Đáp án:
a) `x∈{2;-1}`
b) `x∈{-2;1}`
c)`x∈{2;3;4}`
Giải thích các bước giải:
a) `4x(x+1)=8(x+1)`
`=>4x(x+1)-8(x+1)=0`
`=>(4x-8)(x+1)=0`
`=>`\(\left[ \begin{array}{l}4x-8=0\\x+1=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}4x=8\\x=-1\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=2\\x=-1\end{array} \right.\)
Vậy `x∈{2;-1}.`
b) `x(x-1)-2(1-x)=0`
`=>x(x-1)+2(x-1)=0`
`=>(x+2)(x-1)=0`
`=>`\(\left[ \begin{array}{l}x+2=0\\x-1=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=-2\\x=1\end{array} \right.\)
Vậy `x∈{-2;1}.`
c) `(x-3)^3+3-x=0`
`=>(x-3)^3-(x-3)=0`
`=>(x-3)[(x-3)^2-1]=0`
`=>`\(\left[ \begin{array}{l}x-3=0\\(x-3)^2=1\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=3\\\left[ \begin{array}{l}x-3=1\\x-3=-1\end{array} \right.\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=3\\x=4\\x=2\end{array} \right.\)
Vậy `x∈{2;3;4}.`
