HOC24
Lớp học
Môn học
Chủ đề / Chương
Bài học
chung minh A \(\in\)Z a
tao day
Goi E la mot diem thuoc AC sao cho AB=AE \(\Rightarrow\Delta ABD=\Delta AED\)
\(\Rightarrow\)BD=DE va goc B =goc AED
\(\Rightarrow\)Goc AED >Goc C
\(\Rightarrow\)DC>DE
\(\Rightarrow\)DC>BD
Co :
\(A=1+2^1+2^2+......+2^{2016}\)
\(\Rightarrow2A=2^1+2^2+2^3+.....+2^{2016}+2^{2017}\)
ma A=2A-A=(\(2^1+2^2+2^3+......+2^{2016}+2^{2017}\))-(\(1+2^1+2^2+2^3+....+2^{2016}\))
\(\Rightarrow A=2^{2016}-1\)
\(\frac{2^{2016}}{8}\in N\)
Vay so du cua A khi chia cho 8 la 7
nhan tien cho minh hoi luon bao gio thi Ha Nam thi violympic cap huyen day?Cam on ban nha
vi 5,5 <11 nen(x-11)<0<(x-5,5)
vay gia tri nn cua x la 6 (vi x\(\in N\))
A=3
B=2015