a=2+2^2+2^3+...+2^2004
chung minh rang ;a chia het cho 3,7,15,31
a,A=1/1^2+1/2^2+1/3^2+1/4^2+...+1/50^2.chung minh rang a<2
b;2^1+2^2+2^3+...+2^30.chung minh rang B chia het cho21
chung minh rang
A= 2 mũ 1+ 2 mũ 2+ 2 mũ 3+ ....... +2 mũ 60
a] chung minh rang A chia hết cho 7
b] tìm n biết A+2 =2 mũ n
1.chung minh rang
A=2+2^2+2^3+...+2^30 chia het cho 7
2.chung minh rang neu p la so nguyen to lon hon 3 thi p^2-1chia het cho 24
giai nhanh ho minh nhe!
A=2+22+23+24+....+230
=(2+22+23)+(24+25+26)+...+(228+229+230)
=1(2+22+23)+23(2+22+23)+...+227(2+22+23)
=1.7+23.7+25.7+...+227.7
=7(1+23+25+...+227)
vì 7:7-->A:7
\(A=2+2^2+2^3+2^4+...+2^{29}+2^{30}\)
\(=\left(2^{ }+2^2+2^3\right)+\left(2^4+2^5+2^6\right)+...+\left(2^{28}+2^{29}+2^{30}\right)\)
\(=2.\left(1+2+2^2\right)+2^{^{ }4}.\left(1+2+2^2\right)+...+2^{28}.\left(1+2+2^2\right)\)
\(=2.7+2^4.7+...+2^{28}.7\)
\(=7.\left(2+2^4+...+2^{28}\right)\)
\(\Rightarrow A⋮7\)
chung minh rang A la 1 luy thua cua 2 voi A=A+2^2+2^3+2^4+...+2^20
sai đề rồi bn ơi A=A+2^2+2^3+2^4+...+2^20= ko ra kq nka
nếu đúng thì k , chúc bn hc tốt
Cho a=3^2016+2. Chung minh rang a^2+2 la hop so.
\(a^2+2=3^{4032}+4\cdot3^{2016}+4+2\)
chia hết cho 3
\(\Rightarrow dpcm\)
A=1+2+2^2+2^3+.....+2^2016
chung minh rang A chia het cho 3
A=2^2017-1
cho kết quả rùi
tự làm đi
A=2+2^2+2^3+....+2^9 . Chung minh rang A chia het cho 7
mình nhầm đề nhưng ko sao làm tương tự vậy a
Ta có: A=2+2^2+2^3+...+2^9
=(2+2^2+2^3)+...(2^7+2^8+2^9)
=(2+2^2+2^3)+...+2^6.(2+2^2+2^3)
=14+...+2^6.14
=14.(1+...+2^6)
Vì 14 chc 7 nên 14.(1+...+2^6) hay A chc 7.
Vậy A chc 7 (đpcm)
("chc" là chia hết)
Tick nha bạn!
cho A= 4 + 2^2 +2^3 +2^4+ ...+2^2014 Chung minh rang A chia het cho 1024
Cho A=2+2^2+2^3+...+2^60
Chung minh rang A chia het cho 6
A=2+2^2+2^3+...+2^60
A=(2+2^2)+(2^3+2^4)+...+(2^59+2^60)
A=6+2^2.(2+2^2)+...+2^58.(2+2^2)
A=6+2^2.6+...+2^58.6
A=6.(1+2^2+...+26^58)
Vì 6\(⋮\)6
=>6.(1+2^2+...+2^58) \(⋮\)6
=>A\(⋮\)6
Vậy A chia hết cho 6