Chứng mình rằng :
a) \(\dfrac{1}{4}+\dfrac{1}{16}+\dfrac{1}{36}+\dfrac{1}{64}+\dfrac{1}{100}+\dfrac{1}{144}+\dfrac{1}{196}< \)\(\dfrac{1}{2}\)
b)\(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{63}>2\)
Giup mk nha ! Đang cần gấp lắm rùi !
CMR \(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{8}-\dfrac{1}{16}+\dfrac{1}{32}-\dfrac{1}{64}< \dfrac{1}{3}\)
Tìm x :
\(\dfrac{1}{4}\) . \(\dfrac{2}{6}\) . \(\dfrac{3}{8}\) . \(\dfrac{4}{10}\) . .... . \(\dfrac{30}{62}\) . \(\dfrac{31}{64}\)
\(B=1+\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+.......+\dfrac{1}{63}\)Chứng tỏ rằng \(\dfrac{B}{3}\)không phải là 1 số nguyên
Tính tổng sau đây bằng 2 cách:
\(A=\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}+\dfrac{1}{64}\)
Chứng minh rằng : 1 + \(\dfrac{1}{2}\) + \(\dfrac{1}{3}\) + \(\dfrac{1}{4}\) + ... + \(\dfrac{1}{63}\) < 6
Chứng tỏ rằng:
\(\dfrac{1}{5}+\dfrac{1}{13}+\dfrac{1}{14}+\dfrac{1}{15}+\dfrac{1}{61}+\dfrac{1}{62}+\dfrac{1}{63}< \dfrac{1}{2}\)
Tính:
a) \(45\dfrac{10}{63}-44\dfrac{25}{84}\)
b) \(\left(2\dfrac{1}{3}-1\dfrac{1}{9}\right):4-\dfrac{3}{4}\)
Nhanh nhé ai nhanh mik tick cho!
a)Tìm số nguyên sao cho 4n-5 chia hết cho n-3
b)Chứng minh rằng:
S=\(\dfrac{1}{5}+\dfrac{1}{13}+\dfrac{1}{14}+\dfrac{1}{15}+\dfrac{1}{61}+\dfrac{1}{62}+\dfrac{1}{63}< \dfrac{1}{2}\)