Thay X \(=1,25\) vào biểu thức \(\dfrac{4}{7}\) x \(X+\dfrac{3}{7}-0,75\) x X ta có:
\(\dfrac{4}{7}\) x \(1,25+\dfrac{3}{7}-0,75\) x \(1,25\)
\(=\dfrac{5}{7}+\dfrac{3}{7}-\dfrac{15}{16}\)
\(=\dfrac{80}{112}+\dfrac{48}{112}-\dfrac{105}{112}\)
\(=\dfrac{80+48-105}{112}=\dfrac{23}{112}\)
Vậy X\(=1,25\) giá trị biểu thức \(\dfrac{4}{7}\) x \(X+\dfrac{3}{7}-0,75\) x X là: \(\dfrac{23}{112}\)