Question

Tìm x:

(3x + 4) ⋮ (x - 1)

Answer 1

\(\left(3x+4\right)\)⋮\(\left(x-1\right)\)

⇔ \(\left[3\left(x-1\right)+7\right]\text{⋮}\left(x-1\right)\)

Vì \(3\left(x-1\right)\text{⋮}\left(x-1\right)\)

⇒ \(7\text{⋮}\left(x-1\right)\)

⇒ \(\left(x-1\right)\) ∈\(Ư\left(7\right)=\left\{1;-1;7;-7\right\}\)

Còn lại em tự làm tiếp nha

Answer 2

3x+4=3x-3+7\(⋮\)(x-1)=>3(x-1)+7\(⋮\)(x-1)

mà 3(x-1)\(⋮\)(x-1)

=> 7\(⋮\)(x-1)

=> x-1 là ước của 7

=>\(\left[{}\begin{matrix}x-1=7\\x-1=-7\\x-1=1\\x-1=-1\end{matrix}\right.< =>\left[{}\begin{matrix}x=8\\x=-6\\x=2\\x=0\end{matrix}\right.\)

 

Answer 3

\(3x+4=3\left(x-1\right)+7⋮x-1\)

\(\Rightarrow x-1\inƯ\left(7\right)=\left\{\pm1;\pm7\right\}\)

x - 1	1	-1	7	-7
x	2	0	8	-6