\(a,\left[0,75x+\frac{5}{2}\right]-\frac{4}{7}-\left[-\frac{1}{3}\right]=-\frac{5}{6}\)
\(\Leftrightarrow\left[0,75x+\frac{5}{2}\right]-\frac{4}{7}+\frac{1}{3}=-\frac{5}{6}\)
\(\Leftrightarrow\left[0,75x+\frac{5}{2}\right]=-\frac{5}{6}-\frac{1}{3}+\frac{4}{7}\)
\(\Leftrightarrow0,75x+\frac{5}{2}=-\frac{25}{42}\)
\(\Leftrightarrow0,75x=-\frac{65}{21}\Leftrightarrow x=-\frac{260}{63}\)
\(b,\left[4x-9\right]\left[2,5+-\frac{7}{3}x\right]=0\)
\(\Leftrightarrow\orbr{\begin{cases}4x-9=0\\2,5+-\frac{7}{3}x=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{9}{4}\\x=\frac{15}{14}\end{cases}}\)
Vậy \(x\in\left\{\frac{9}{4};\frac{15}{14}\right\}\)
Tham khảo nhé phamthiminhanh
a) \(\left(0,75x+\frac{5}{2}\right)-\frac{4}{7}-\left(-\frac{1}{3}\right)=-\frac{5}{6}\)
=> \(0,75x+\frac{5}{2}-\frac{4}{7}+\frac{1}{3}=-\frac{5}{6}\)
=> \(0,75x=-\frac{5}{6}-\frac{5}{2}+\frac{4}{7}-\frac{1}{3}\)
=> \(0,75x=-\frac{65}{21}\)
=> \(x=-\frac{260}{63}\)
b) \(\left(4x-9\right)\left(2,5+-\frac{7}{3}x\right)=0\)
=> \(10x-\frac{28}{3}x^2-22,5+21x=0\)
=> \(-\frac{28}{3}x^2+31x-22,5=0\)
=> Phần còn lại bạn tự giải tiếp nhé!
