Question

6. Tính nhanh:

a. M = 1 - ( 1/2 + 1/4 + 1/8 + 1/16 + 1/32 )

* Đây là dạng toán nâng cao lớp 4 nhưng mik cho lên lớp 5.

Answer 1

\(M=1-\left(\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}\right)\)

\(=1-\left(\dfrac{3}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}\right)\)

\(=1-\left(\dfrac{7}{8}+\dfrac{1}{16}+\dfrac{1}{32}\right)\)

\(=1-\left(\dfrac{15}{16}+\dfrac{1}{32}\right)\)

\(=1-\dfrac{31}{32}=\dfrac{1}{32}\)