A={2+2mũ2+2mũ3+2mũ4+… +2mũ20 Question A={2+2mũ2+2mũ3+2mũ4+… +2mũ20 in progress 0 Môn Toán Cherry 4 years 2020-10-31T07:25:52+00:00 2020-10-31T07:25:52+00:00 2 Answers 133 views 0
Answers ( )
Đáp án: A=2^20-2
Giải thích các bước giải:
A=2+2^2+2^3+2^4+…+2^20
2.A=2^2+2^3+2^4+…+2^20
2.A-A=(2^2+2^3+2^4+…+2^20)
– (-2+2^2+2^3+2^4+2^20
A=2^20-2
Cho mk xin ctlhn
`A = 2+2²+2³+2^4 + … + 2^20`
`⇒ 2A = 2² + 2³ + 2^4 + 2^5 + … + 2^21`
`⇒ 2A – A = (2² + 2³ + 2^4 + 2^5 + … + 2^21) – (2+2²+2³+2^4 + … + 2^20)`
`⇒ A = 2^21 – 2`
Xin hay nhất !