Toán Lớp 6: tính M=2+2^2+2^3+2^4+…….+2^2017+2^2018
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Toán Lớp 6: tính M=2+2^2+2^3+2^4+…….+2^2017+2^2018
Comments ( 2 )
Giải đáp:
M = $2^{2019}$ – 2
Lời giải và giải thích chi tiết:
M = 2 + $2^{2}$ + $2^{3}$ + … + $2^{2017}$ + $2^{2018}$
2M = $2^{2}$ + $2^{3}$ + $2^{4}$ + …. + $2^{2018}$ + $2^{2019}$
2M – M = $2^{2019}$ + $2^{2018}$ – $2^{2018}$ + $2^{2017}$ – $2^{2017}$ + … + $2^{2}$ – $2^{2}$ -2
M = $2^{2019}$ – 2
Vậy M = $2^{2019}$ – 2
M=2+2^2+ 2^3+…+2^2017 +2^2018
2M= 2^2 +2^3 +2^4+ …+2^2019
=>2M-M=(2^2 +2^3 +2^4 +….+2^2019 )-(2+2^2 +2^3 +….+2^2018 )
=>M=2^2019 -2
\text{# Mạc}