3A=3.1.2+3.2.3+....+3.101.102
=1.2(3-0)+2.3(4-1)+....+102.102(103-100)
=1.2.3-0.1.2+2.3.4-1.2.3+....+101.102.103-100.101.102
=-0.1.2+101.102.103
=101.102.103=1061106
1.2+2.3+3.4+4.5...+99.100+101
Bài 5 :
a) Chứng minh rằng : 1/1.2 + 1/3.4 + 1/5.6 + ... + 1/199.200/ 1/101 + 1/102 + 1/103 + ... + 1/200 = 1
b) So sánh A = 1 mũ 2/1.2 x 2 mũ 2/2.3 x 3 mũ 2/3.4 x 99 mũ 2/99.100 x 100 mũ 2/100.101 và B = 2 mũ 2/1.3 x 3 mũ 2/2.4 x 4 mũ 2/3.5
x .... x 59 mũ 2/58.60
D = 5/2.3 - 7/3.4 + 9/4.5 - 11/5.6 + ... + 101/50.51 + 102/51/52
Tính
a) S= 1.2+2.3+3.4+...+32.33
b) S= 1.2+2.3+3.4+...+49.50
S=1+2+2^2+2^3+2^4+...+2^100
S=1.2+2.3+3.4+4.5+...+99.100+100.101
Q=1^2+2^2+3^2+...+100^2+101^2
Chứng tỏ rằng:
\(\dfrac{\dfrac{1}{1.2}+\dfrac{1}{3.4}+...+\dfrac{1}{199.200}}{\dfrac{1}{101}+\dfrac{1}{102}+...+\dfrac{1}{200}}=1\)
Giúp mình với📖
Tính nhanh
C=1.2+2.3+3.4+...+2014.2015
K=1.2+2.3+3.4+..+(n-1).n
A= 1.2+2.3+3.4+...........+ 2020.2021
A=1.2+2.3+3.4+...+99.100
