Question

Tìm ĐK của x để |B|+3<2x-1

B=(4-3x)/4

Answer 1

\(\left|B\right|\)+3<2x-1

\(\Leftrightarrow\)\(\left[{}\begin{matrix}B+3< 2x-1\\-B+3< 2X-1\end{matrix}\right.\)

+ B+3<2x-1

\(\Leftrightarrow\)\(\dfrac{4-3x}{4}+3< 2x-1\)

\(\Leftrightarrow\dfrac{4-3x}{4}+\dfrac{12}{4}< 2x-1\)

\(\Leftrightarrow4-3x+12< 2x-1\)

\(\Leftrightarrow16-3x< 2x-1\)

\(\Leftrightarrow-5x< -17\)

\(\Leftrightarrow x>\dfrac{17}{5}\)

+ -B+3<2x-1

\(\Leftrightarrow\)\(\dfrac{-4+3x}{-4}\)+3<2x-1

\(\Leftrightarrow\dfrac{-4+3x}{-4}+\dfrac{-12}{-4}< 2x-1\)

\(\Leftrightarrow-4+3x-12< 2x-1\)

\(\Leftrightarrow x< 15\)

Vậy:ĐK của x để \(\left|B\right|+3< 2x-1\)

                             B=\(\dfrac{4-3x}{4}\)                

                            \(\left(x|x>\dfrac{17}{5};x< 15\right)\)