tim cac chu so a,b biet: aabb chia het cho 99
tim cac chu so a,b biet aabb chia het cho 33
tim chu so a de :
b) B=100...0100...0a5 chia het cho 37
c) C=100...0100..0a2 chia het cho 27
chung minh neu p la so nguyen to thi
2.3.4. .... .(p-3).(p-2)-1 chia het cho p
a)so sanh E=2018^99-1/2018^100-1 va F=2018^98/2018^99-1
b)Tim so nguyen to ab (a>b>0),biet ab-ba la so chinh phuong
c)Cho abc la so tu nhien co 3 chu so .Tim gia tri lon nhat cua A={abc/a+b+c}+1918
1. a) tim 2 so tu nhien a,b (a,b>0);biet (a,b)=9;[a,b]=54
b) tim 2 so tu nhien a,b (a,b>0);biet a+b=42; [a,b]=72
b, tim n de [n+10].[n+21]=124689
c, tim cac chu so a,b biet aabb la so chinh phuong
Tinh tong: a) 9 + 99 + 999 + ... + 999...999 ( co 10 c/s 9 )
b) Tim x, biet: 1/21 + 1/28 = 1/36 +... + 2/x(x+1) = 2 / 9
tim hai so tu nhien a,b >0 biet ab =216 va (a,b)=6
tim ab biet aabb-ab=1180
chi can ket qua thoi
tim a ;b thuoc so tunhien khac 0 biet
a, 1/a+1/b=5/9
b,a.a+b+2=2ab
