Tim hai so nguyen to a va b sao cho: 3a-13=b(a-3)
Trinh bay cach lam lun he
bai 3 cho p la so nguyen to lon hon 3
A, chung to p co dang 6k+1 hoac 6k+5
B, cho p va 8p-1 la so nguyen to. chung to 8p+1 la hop so
bai 4
A, tim a va b biet rang a.b=320 va BCNN(a,b)=160
B, tim so tu nhien a nho nhat co 3 chu so sao cho khi chia a cho 11 du 5 va chia cho 13 thi du 8
tim so nguyen to p sao cho:
a,p+2 va p+4 la so nguyen to
b,p+2 va p+6 va p+8 la so nguyen to
c,p+10 va p+14 la so nguyen to
tim so nguyen a sao cho a-1 la Ư của a+6
tim so nguyen a sao cho 3a+5la B cua a-2
a, Cho ( a,b) = 1 . Chung minh rang (a.b, a+b)=1
b, Cho (a,b)= 1. Tim UCLN (11a+2b , 18a +5b)
C,, Cho A = m+n ; B=m^2+n^2.Trong do m va n la cac so tu nhien nguyen to cung nhau. Tim UCLN (A,B)
d, Tim cac so tu nhien n sao cho n^3 - n^2 + n-1la so nguyen to
Bai1 a,cho n thuoc N. Chung minh rang 6n+5 va 4n+3 la 2 so nguyen to cung nhau
b, tim so nguyen x sao cho x+2016 la so nguyen duong nho nhat
Bai1:cmr 2 stn dang 2n+3 va 3n+2 bao gio cung la 2 so nguyen to cung nhau.
Bai 2:tim 2 chu so a ; b biet (a+b)(a-b)=20.
Bai 3: tim 2 stn lien tiep co 2 chu so sao cho 1 so chia het cho 25, so kia chia het cho 4.
Bai 4: tim a;b biet a.b=360 va BCNN(a,b)=60
Tim so nguyen to p sao cho cac so sau cung la cac so nguyen to :
a) p + 10 va p + 20
b)p+14 va p + 20
Bai 1: a)Tim so tu nhien a biet 1960va2002 chia cho a cung co so du la 28
b)Tim 2 sop tu nhien a va b , biet :BCNN(a,b)=300;UCLN(a,b)=15 va a+15=b
Bai 2:a)Tong sau la binh phuong so nao ?
S=1+3+5+7+...+199
b) Cho so ab va so ababab
1)chung to ababab la boi cua ab
2)So 3 va 10101 co phai la uoc cua ababab khong , vi sao?
Bai 3
a)Hay viet them dang sau so 664 ba chu so de nhan duoc sdo co 6 chu so chia het cho 5,9,11
b)Tim so nguyen x thuoc Z biet rang :
(x^2-1)(x^2-4)<0
Bai 4 :tim so nguyen x va y biet: xy-x+2y=3