A = \(2^2.\left(1^2+2^2+3^2+...+10^2\right)=4.385=1540\)

B=\(3^2.\left(1^2+2^2+3^2+...+10^2\right)=385.9=3465\)

b. S=(2+4+6+...+19+20)^2

P=(3+6+9+...+30)^2

\(S=2^2+4^2+....+20^2=?\)

\(=\left(2.1\right)^2+\left(2.2\right)^2+\left(2.3\right)^2+....+\left(2.10\right)^2\)

\(=2^2.1^2+2^2.2^2+2^2.2^3+...+2^2.10^2\)

\(=2^2.\left(1^2+2^2+3^2+...+10^2\right)\)

\(=2^2.385\)

\(=4.385\)

\(=1540\)

S=2²+4²+...+20²

=> 1/2 .S=1²+2²+...+10²

=> 1/2 .S=385

=> S = 385 . 2

=> S = 770

P=(1.3)²+...+(10.3)

   =3²(1²+...+10²)

   =9.385 = 3465

Bài 1:

A = 1 + 3 + 3² + ... + 3¹⁰⁰

=> 3A = 3 + 3² + ... + 3¹⁰¹

=> 2A = 3¹⁰¹ - 1

=> A = \(\frac{3^{101}-1}{2}\)

B = 1 + 4² + 4⁴ + ... + 4¹⁰⁰

=> 8B = 4² + 4⁴ + ... + 4¹⁰²

=> 7B = 4¹⁰² - 1

=> B = \(\frac{4^{102}-1}{7}\)

Bài 2:

a) S₁ = 2² + 4² + ... + 20²

=> S₁ = 2²(1+2²+...+10²)

=> S₁ = 2².385

=> S₁ = 1540

b) S₂ = 100² + 200² + ... + 1000²

=> S₂ = 100²(1+2²+...+10²)

=> S₂ = 100².385

=> S₂ = 3850000

\(B=2^3+4^3+6^3+...+20^3\)

\(=2.\left(1^3+2^3+3^3+...+10^3\right)\)

\(=2.3025\)

\(=6050\)

Ta có B = 2³ + 4³ + 6³ + ... + 20³

             = 2³.(1³ + 2³ + 3³ + ... + 10³)

             = 2³.3025

             = 8. 3025

             = 24200

quên bài tôi sai rồi @@

ai nhanh nhất,đúng nhất mình  cho