C = \(\dfrac{3}{2}\) + \(\dfrac{3}{4}\) + \(\dfrac{3}{8}\)+ \(\dfrac{3}{16}\)+...........+\(\dfrac{3}{128}\)
C\(\times\)2 = 3 + \(\dfrac{3}{2}\) + \(\dfrac{3}{4}\) + \(\dfrac{3}{8}\) + \(\dfrac{3}{16}\)+...+\(\dfrac{1}{64}\)
C\(\times\)2 - C = 3 - \(\dfrac{3}{128}\)
C = \(\dfrac{381}{128}\)
Câu E em xem lại đề nhé