Tim so co n = abcd biet n + a + b + c + d = 1997
cho 4 sn a,b,c,d sao cho 2b=a+c; 2a=b+d ; c^2+d^2<4 .tim a biet b=2
Tim cac so a,b,c,d biet
abcd x 5 + 6 = dcba
cho a+b=c+d=e+f voi a, b , c ,d,e,f la cac so nguyen phan biet nho hon 20 tim a+b
tim a,b,c biet : abcd+abc+ab+a=3884
tim cac so tu nhien a,b c,d biet
2013/2018=1/a+1/b+1/c+1/d+1/e
1) chung to rang(a-b)-(c-d)+(b+c)=a+d
2) tim x thuoc Z biet x+(x-5)-(x-25)=-1984
Tim cac chu so a,b,c,d biet a× bcd×abc=abcabc
nha van anh sechxipia sinh nam nao va mat nam nao?
a]nam sinh la so [abcd ] biet a+b=c;ab+d=19 ab-d=11
b] mat nam la so [abcd] biet ab=cd ; b+c=7 ; b chia c = 6