\(ab+acd+abcd=2005=>d=5\)
\(=>\left(10a+b\right)+\left(100a+10c+5\right)+\left(1000a+100b+10c+5\right)=2005\)
\(=>1110a+101b+20c+10=2005\)
\(=>1110a+101b+20c=1995\)
\(=>a=1\)
\(=>1110+101b+20c=1995\\ \)
\(=>101b+20c=885\)
=> bạn viết đề sai 100%
Nếu đề chuyển thành cd+acd+abcd=2005
Mình giúp bạn
Vì cd+acd+abcd=2005 => d=5
=>c5+ac5+abc5=2005
=>(10c+5)+(100a+10c+5)+(1000a+100b+10c+5)=2005
=>1100a+100b+30c+15=2005
=>1100a+100b+30c=1990
=>a=1
=>1100+100b+30c=1990
=>100b+30c=890
=>b=8;c=3
rồi a=1;b=8;c=3;d=5