Cho M = 11 + 13 + 15 + . . . + 99 . Hỏi M có chia hết cho hay không?
Cho M = 11 + 13 +15 + ... + 99. Hỏi M có chia hết cho 2 hay không?
+ Số số hạng là: 45 số hạng
+ Vậy M không chia hết cho 2 vì tổng lẻ của các số lẻ là một số lẻ
cho A + 11 + 13 + 15+...+99
hỏi A có chia hết cho 2 không
có vì 2 số lẽ cộng với nhau ra số chẳn
Cho A = 13! - 11!
a) A có chia hết cho 2 hay không ?
b) A có chia hết cho 5 hay không ?
c) A có chia hết cho 155 hay không ?
bài 1:cho a chia hết cho m;b chia hết cho m và a+b+c không chia hết cho m ;chứng minh c không chia hết cho m
bài 2:so sánh
a)21^15 và 27^5*49^8
b)3^99 và 11^21
bài 3:chứng minh
A=1+3+3^2+3^3+..........+3^11 chia hết cho13
Cho A=13! -11!
a) A có chia hết cho 2 hay không?
b) A có chia hết cho 5 hay không?
c) A có chia hết cho 155 hay không?
*13! chia hết cho 2
11! chia het cho 2=>13!-11! chia hết cho 2
*13! chia het cho 5
11! chia het cho 5=>3!-11! chia het cho 5
*155=5.31
13! ko chia hết cho 5.31
11! ko chia het cho 5.31=>13!-11! ko chia het cho 155
a)A chia hết cho 2
b)A chia hết cho 5
c)A ko chia het cho 155
**** GIÙM MÌNH NHA
Cho A=13! -11!
a) A có chia hết cho 2 hay không?
b) A có chia hết cho 5 hay không?
c) A có chia hết cho 155 hay không?
a) 13! = 13.12.11....5.4.3.2.1 => 13! chia hết cho 2 và 5
11! = 11.10.9....5.4.3.2.1 => 11! chia hết cho 2 và 5
=> A = 13! - 11! chia hết cho 2 và 5
c) A = 13! - 11! = 13.12.11! - 11! = (13.12 - 1) .11! = 155.11! chia hết cho 155
Vậy A chia hết cho 155
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CHO A = 13! - 11!
A) A CÓ CHIA HẾT CHO 2 HAY KHÔNG ?
B) A CÓ CHIA HẾT CHO 5 HAY KHÔNG ?
C) A CÓ CHIA HẾT CHO 155 HAY KHÔNG ?
\(A=13!-11!\)
\(A=11!\cdot12\cdot13-11!\)
\(A=11!\left(12\cdot13-1\right)\)
\(A=11!\cdot155\)
\(\Rightarrow\)A chia hết cho 2 ( vì trong 11! chứa thừa số 2 )
A chia hết cho 5
A chia hết cho 155
a)A có chia hết cho 2
b)A có chia hết cho 5
c)A có chia hết cho 155
Cho A=13!-11!.
a)A có chia hết cho 2 hay không?.
b)A có chia hết cho 5 hay không?.
c)A có chia hết cho cả 2 và 5 hay không?
A=13!-11!=6187104000
a) A chia hết cho 2 vì số tận cùng của A là số 0
b) A chia hết cho 5 vì số tận cùng của A là số 0
c)A chia hết cho 2 và 5 vì số tận cùng của A là số 0
cho A = 13! - 11!
a\ A có chia hết cho 2 hay không
b\A có chia hết cho 5 hay không
c/A có chia hết cho 155 hay không