Câu 5:
a) \(\left|3-2x\right|=\dfrac{1}{2}\)
Khi \(x\ge0\), ta có
\(3-2x=\dfrac{1}{2}\)
\(2x=\dfrac{5}{2}\)
\(x=\dfrac{5}{4}\)
Khi \(x< 0\), ta có
\(-\left(3-2x\right)=\dfrac{1}{2}\)
\(-3+2x=\dfrac{1}{2}\)
\(2x=\dfrac{7}{2}\)
\(x=\dfrac{7}{4}\)
b) \(\dfrac{x-1}{4}=\dfrac{10}{8}\)
\(\dfrac{x-1}{4}=\dfrac{5}{4}\)
\(x-1=5\)
\(x=6\)
Câu 6:
Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{a}{b}=\dfrac{c}{d}=\dfrac{a+c}{b+d}=\dfrac{a-c}{b-d}\)
hay \(\dfrac{a+c}{b+d}=\dfrac{a-c}{b-d}\)
Câu 5:
a: Ta có: \(\left|3-2x\right|=\dfrac{1}{2}\)
\(\Leftrightarrow\left[{}\begin{matrix}3-2x=\dfrac{1}{2}\\3-2x=-\dfrac{1}{2}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=\dfrac{5}{2}\\2x=\dfrac{7}{2}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{4}\\x=\dfrac{7}{4}\end{matrix}\right.\)
b: Ta có: \(\dfrac{x-1}{4}=\dfrac{10}{8}\)
\(\Leftrightarrow x-1=5\)
hay x=6
