4(x - 1) + 6x \(\le\) 3(x + 1) + 15
<=> 4x - 4 + 6x \(\le\) 3x + 3 + 15
<=> 7x \(\le\) 22
<=> x \(\le\) \(\dfrac{22}{7}\) S = {x|x\(\le\) \(\dfrac{22}{7}\)}
4(x-1) + 6x ≤ 3(x+1) + 15
<=> 4x + 6x - 3x ≤ 3 + 15 + 4
<=> 7x ≤ 22 <=> x ≤ 22/7
\(4\left(x-1\right)+6x\le3\left(x+1\right)+15\)
\(\Leftrightarrow4x-4+6x\le3x+3+15\)
\(\Leftrightarrow10x-4\le3x+18\Leftrightarrow7x\le22\Leftrightarrow x\le\dfrac{22}{7}\)
Vậy tập nghiệm của BFT là : S = { x | x \(\le\)22/7 }