Question

tìm các chữ số a; b; c khác 0 sao cho: abc= ab x ac x 7

Answer 1

\(\frac{ }{abc}\)  \(=\frac{ }{ab}\)\(\frac{ }{.ac}\)\(\frac{ }{.7}\) 

<=> a.100+b.10+c=(a.10+b).(a.10+c).7

<=> a.100+b.10+c=[(a.10+b).a.10+(a.10+b).c].7

<=> a.100+b.10+c=(a².100+b.a.10+a.10.c+b.c).7

<=> a.100+b.10+c=[(a².100+a.10)+(b.a.10+b.c)].7

......

 

Answer 2

a=2;b=3;c=5