Question

Determinați valorile lui a si b si toate numerele de forma ab stiind ca : ab-ba=9 ab-ba=18

Answer 1

ab=10a+b si ba=10b+a⇒ab-ba=10a+b-10b-a=9a-9b=9(a-b)
9(a-b)=9⇒a-b=1⇒a=b+1⇒ab={10,21,32,43,54,65,76,87,98}
9(a-b)=18⇒a-b=2⇒a=b+2⇒ab={20,31,42,53,64,75,86,97}