voi a,b la cac so nguyen duong sao cho a+1 va b+2007 chia het cho 6
cmr 4a+a+b chia het cho 6
cho a,b,c la cac so nguyen duong co a + b +c chia het cho 2 chung minh P=a2 + b2 + c2 la hop so
bai 1 tim cac stn x y z sao cho x+y+z=xyz
bai 2cmr neu m^2+mn+n^2chia het cho 9 voi m ,n la cac stn thi m,n chia het cho 3
bai 3 tim stn n nho nhat de cac phan so sau toi gian
7/n+9.8/n+10,...,31/n+33
bai 4chung to rang phan so m^3+2m/m^4+3m^2 +1 toi gian
bai 5 a,cmr khong ton tai so chinh phuong nao co dang abab
b,cho 51 so nguyen duong khong vuot qua 100 cmr ton tai 2 so trong 51 so noi tren ma 1 so chia het cho so con lai
c,tim cac so co 3 chu so sao cho hieu cua so ay va gom 3 chu so ay viet theo thu tu nguoc lai la mot so chinh phuong
bai 6cmr A=2x(x+y-1)+y^2+1 luon nhan gia tri khong am voi moi x,y
bai 7 tim hai so nguyen duong sao cho tong ,hieu thuong (so lon chia cho so nho )cua chung cong lai duoc 38
bai 8 cho ba so a,b,c thoa man a/2009=b/2010=c/2011
tinh gia tri cua bieu thuc M=4(a-b)(b-c)-(c-a)^2
tim tat ca cac so nguyen duong n sao cho:2^n-1 chia het cho 7
B1: cho a,b,c la cac so nguyen duong
CMR:neu a /b >hoac bang c/d thi a/b > hoac bang a+c/b+d > hoac bang c/d
B2: Tim PS nho nhat khac 0 sao cho khi chia no cho 14/9 ; cho 45/27 deu duoc thuong la cac so tu nhien
B3:CMR: 1/2^2 + 1/4^2 + 1/6^2 +....+ 1/100^2 < 1/2
B1. Cho f(1)=1008,f(1)+f(2)+...+f(n)=n^2.f(n) f(n)la ham so duong
tinh f(2015)
B2 Cho cac so nguyen to q,p,r,s sao cho cac so sau deu la so nguyen to p^s+s^q,q^s+s^r,r^s+s^p
tim cac so p,q,r,s
B3 co a,b,c duong a mu 3+bmu3=c^3
so sanh a^2015+b^2015 va c^2015
tim so nguyen duong a lon nhat sao cho 2004! chia het cho 7a
hay tim tat ca so nguyen duong a,b,c doi mot nguyen to cung nhau sao cho a<b<c va a+b+c+ab+bc+ac chia het cho abc
lam duoc minh se tang tick
TIM N LA SO NGUYEN SAO CHO
a , 3n +11 chia het cho n
b , 2n - 7 chia het cho n+ 2
c , n2 + 2n + 10 chia het cho n+ 1