cdab - abcd = 4356
(cd x 100 + ab) - (ab x 100 + cd) = 4356
cd x 100 + ab - ab x 100 - cd = 4356
cd x 99 + ab - ab x 100 = 4356
cd x 99 - ab x 99 = 4356
(cd - ab) x 99 = 4356
(cd - ab) = 4356 : 99 = 44
ab là:
(92 - 44) : 2 = 24
cd là:
92 - 24 = 68
cdab-abcd=4356
<=> 100cd+ab-(100ab+cd)=4356
<=> 100cd+ab-100ab-cd=4356
<=> 99.cd - 99.ab=4356
<=> cd-ab=44
Lại có: cd+ab=92
=> cd=\(\frac{44+92}{2}=68\)
ab=68-44=24
Đáp số: ab=24; cd=68
cdab - abcd = 4356
( cd x 100 + ab ) - ( ab x 100 + cd ) = 4356
cd x 100 + ab - ab x 100 - cd = 4356
cd x 99 - ab x 99 = 4356
( cd - ab ) x 99 = 4356
cd - ab = 4356 : 99
cd - ab = 44
ab = ( 92 - 44 ) : 2 = 24
cd = 92 - 24 = 68
Ta có : cdab - abcd = 4356
\(\Rightarrow\) ( cd . 100 + ab ) - ( ab . 100 + cd ) = 4356
\(\Rightarrow\) cd . 100 + ab - ab . 100 = 4356
\(\Rightarrow\) cd . 99 + ab - ab . 100 = 4356
\(\Rightarrow\) cd . 99 - ab .99 = 4356
\(\Rightarrow\) ( cd - ab ) . 99 = 4356
\(\Rightarrow\) ( cd - ab ) = 4356 : 99 = 44
Vậy ta có : ab = ( 92 - 44 ) : 2 = 24
cd = 92 - 24 = 68
