ab-(axb)=4(a+b)
(10a+b)-(axb)=4(a+b)
10a+b-(axb)=4a+4b
6a-3b-axb=0
6a-b(a+3)=0
6a=b(a+3)
b=(6a)/(a+3)
b=(6a+18-18)/(a+3)=(6a+18)/(a+3)- 18/(a+3)=6- 18/(a+3)
a si b=cifre de la 1 la 9, rezulta ca a+3 divide 18:
a+3={1,2,3,6,9,18}
a={-2, -1, 0, 3, 6, 15}
dar a= cfra de la 1 la 9, rezulta a={3;6}
a=3, b=(6a)/(a+3)=18/6=3, b=3, ab=33
a=6, b=(6a)/(a+3)=36/9=4, b=4, ab=64
