\(D=4+4^2+4^3+...+4^{100}\)
=>\(4D=4^2+4^3+...+4^{101}\)
=>\(4D-D=4^{101}+4^{100}+4^{99}+...+4^3+4^2-4^{100}-4^{99}-...-4^2-4\)
=>\(3D=4^{101}-4\)
=>\(D=\dfrac{4^{101}-4}{3}\)
`#3107.101107`
\(D=4 + 4^2 + 4^3 + 4^4 + …. + 4^{100}\)
\(4D=4^2 + 4^3 + 4^4 + ... + 4^{101}\)
\(4D - D = (4^2 + 4^3 + 4^4 ... + 4^{101}) - (4 + 4^2 + 4^3 + ... + 4^{100})\)
\(3D = 4^2 + 4^3 + 4^4 + ... + 4^{101} - 4 - 4^2 - 4^3 - ... - 4^{100}\)
\(3D = 4^{101} - 4\)
\(D = \dfrac{4^{101} - 4}{3}\)
Vậy, \(D=\dfrac{4^{101} - 4}{3}.\)