Cho A = 13! - 11!
a) A có chia hết cho 2 không ?
b) A có chia hết cho 5 không ?
c) A có chia hết cho 155 không ?
Cho A = 13! - 11!
a) A có chia hết cho 2 không ?
b) A có chia hết cho 5 không ?
c) A có chia hết cho 155 không ?
A=13!-11!
A=1.2.3....12.13-1.2.3....10.11
A=618 710 400
a)A chia hết cho 2 ( vì có số cuối là 0)
b)A chia hết cho 5( vì có số cuối là 0)
C)A chia hết cho 155( vì a>155 và 155=5.31)
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 ?
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 155 hay không
Cho A = 13! - 11!
a) A có chia hết cho 2 hay không ?
b) A có chia hết cho 5 không ?
c) A có chia hết cho 155 hay không ?
TRẢ LỜI HỘ MÌNH NHA NGAY BÂY GIỜ NHÉ !!!!!!
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 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
Phần b) và a) mk gộp vào rồi nhé. Duyệt nha bạn . Chúc bạn học tốt
Ta có:
A = 13! -11!
= 11!(12.13-1)
= 11! . 155
Mà 11! chia hết cho 2, 5 nên A chia hết cho 2 và 5.
Mà 155 chia hết cho 155 nên A chia hết cho 155
A = 13! - 11! = 1 . 2 . 3 . 4 . ...... . 13 - 1 . 2 . 3 . 4 . .... . 11
= 1 . 2 . 3 . 4 . .... . 11 ( 12 . 13 - 1 )
= 1 . 2 . 3 . 4 . .... . 11 ( 156 - 1 )
= 1 . 2 . 3 . 4 . .... . 11 . 155
vì tích trên có chứa thừa số 2 ; 5 ; 155
=> A chia hết cho 2 ; cho 5 ; cho 155
chúc bạn học giỏi
70.Cho n là số tự nhiên. Chứng minh rằng :
a) (n+10)(n+15) chia hết cho 2.
b) n(n+1)(n+2) chia hết cho 2 và 3
c) n(n+1)(2n+1) chia hết cho 2 và 3
76. Cho A = 13! - 11!
a) A có chia hết cho 2 không ?
b) A có chia hết cho 5 không ?
c) A có chia hết cho 155 không ?
70.a,nếu n chẵn thì n+10 chẵn chia hết cho 2,nếu n lẻ thì n+15 chẵn chia hết cho 2(vì bất kì một số nào nhân với số chẵn đều ra số chẵn)
làm tương tự vậy là được thui
A=13!-11!=11!.(12.13-1)=11!.155=1.2.3.4.5.....11.155
vì trong tích có các thừa soos2,5,155 nên A chia hết cho 2,5,155
70.Cho n là số tự nhiên. Chứng minh rằng :
a) (n+10)(n+15) chia hết cho 2.
b) n(n+1)(n+2) chia hết cho 2 và 3
c) n(n+1)(2n+1) chia hết cho 2 và 3
76. Cho A = 13! - 11!
a) A có chia hết cho 2 không ?
b) A có chia hết cho 5 không ?
c) A có chia hết cho 155 không ?
Vì n là số tự nhiên nên sảy ra 2 trường hợp
+ n là số chẵn thì n có dạng 2a
Thay n = 2a ta có : (n + 10) ( n + 15) = (2a + 10)(n + 15)
= 2(a + 5)(n + 15) chia hết cho 2
+ n là số lẻ thì n có dạng 2a + 1
Thay n = 2a + 1 ta có : (n + 10)(n + 15) = (2a + 11)(2a + 16)
= 2(2a + 11)(a + 8) chia hết cho 2
Vậy với mọi số tự nhiên n thì (n + 10)(n + 15) chia hết cho 2 (đpcm)