`A=3+3^2+3^3+...+3^100`
`3A=3(3+3^2+...+3^100)`
`3A=3^2+3^3+...+3^101`
`3A-A=(3^2+3^3+...+3^101)-(3+3^2+...+3^100)`
`2A=3^2+3^3+...+3^101-3-3^2-...-3^100`
`2A=3^101-3`
`A=(3^101-3)/2`
`A=3+3^2+3^3+...+3^100`
`3A=3(3+3^2+...+3^100)`
`3A=3^2+3^3+...+3^101`
`3A-A=(3^2+3^3+...+3^101)-(3+3^2+...+3^100)`
`2A=3^2+3^3+...+3^101-3-3^2-...-3^100`
`2A=3^101-3`
`A=(3^101-3)/2`
A=1/2+2/2^2+3/2^3+...+100/2^100
B=1/3+2/3^2+3/3^2+...+100/3^100
A=1/3-2/3^2+3/3^3-4/3^4-......-100/3^100. Chứng minh A nhỏ hơn 3/16
3)tính
A=1+2+2^2+…+2^100
B=3-3^2+3^3-3^4+…+2^99-3^100
3)tính
A=1+2+2^2+…+2^100
B=3-3^2+3^3-3^4+…+2^99-3^100
Tinh:
A= (10^3-1}^1.(10^3-2)^2.(10^3-3)^3.........(10^3-100)^100
Chứng minh rằng: A=\(\dfrac{1}{3}-\dfrac{2}{3^2}+\dfrac{3}{3^3}-\dfrac{4}{3^4}+...+\dfrac{99}{3^{99}}-\dfrac{100}{3^{100}}< \dfrac{3}{16}\)
Cho A= 1+3+32+33+...+3100
B= 3100 : 2.Tính B-A
Bài 1: Tính
a) S=1+3+3 mũ 2 +3 mũ 3 +...+3 mũ 100
b) A=1+3 mũ 2 +3 mũ 4 +...+3 mũ 100
Bài 1: Co A= 3^0 + 3^2 + 3^3 + ... + 3^2002
a) Tính A
b) Chứng minh rằng A chia hết cho 7
Bài 2: Cho C = 3+ 3^2 + 3^3 +...+ 3^100
a) Tính C
b) Tìm n biết 2.C+3=3^n
Bài 3 : Tính B= 3+ 3^2+3^3+..+3^100
Chứng minh rằng :
A=1/3-2/3^2+3/3^3-4/3^4+...+99/3^99-100/3^100<3/6