1+\(\dfrac{1}{3}\)+\(\dfrac{1}{5}\)+..............+\(\dfrac{1}{99}\)
= 2 - \(\dfrac{1}{3}\)+\(\dfrac{1}{3}\)- \(\dfrac{1}{5}\)+........+\(\dfrac{1}{97}\)-\(\dfrac{1}{99}\)
= 2 - \(\dfrac{1}{99}\)
= \(\dfrac{197}{99}\)
Tính: 1 - 3 + 5 - 7 + 9 - 11 + ... +97 - 99 + 101
1. 1+ (-2) + 3+ (-4) + . . . +19 + (-20)
2. 1 - 2 + 3- 4 + . . . + 99 - 100
3. -1 + 3 -5 + 7 - . . . +97 - 99
4. 1+ 2 - 3+ 4 + . . . +97 + 98 - 99 - 100
a) 100-99+98-97+...+4-3+2-1
b) 99-97+95-93+...+7-5+3-1
Cho A= 1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6 + ... + 1/99 + 1/100. Chứng tỏ 7/12 < A <5/6
chứng minh rằng
1+1/3+1/5+1/7+...+1/99-(1/2+1/4+1/6+...+1/100)=1/51+1/52+...+1/100
Tính giá trị biểu thức :
\(\dfrac{1}{2}-\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\left(\dfrac{1}{4}+\dfrac{2}{4}+\dfrac{3}{4}\right)-\left(\dfrac{1}{5}+\dfrac{2}{5}+\dfrac{3}{5}+\dfrac{4}{5}\right)+\left(\dfrac{1}{6}+\dfrac{2}{6}+\dfrac{3}{6}+\dfrac{4}{6}+\dfrac{5}{6}\right)-\left(\dfrac{1}{7}+\dfrac{2}{7}+\dfrac{3}{7}+\dfrac{4}{7}+\dfrac{5}{7}+\dfrac{6}{7}\right)+...+\left(100+...+\dfrac{99}{100}\right)\)
1.
(n+5) chia hết cho (n-2)
(2n+1)chia hết cho(n-5)
2.
S=1+2-3-4+5+6-7-8+.....-99-100
1+2-3-4+5+6-7-8+....+97+98-99-100
a.1+(-3)+5+(-7)+....+17+(-19)
b.1-4+7-10+....-100+103
c.1+2-3-4+5+6-7-8+...-99-100+101+102
