[tex]\bf\dfrac{15}{4}-1=[/tex]
[tex]\bf\dfrac{15}{4}-\dfrac{1}{1}=[/tex]
[tex]\bf\dfrac{15}{4}-\dfrac{1\cdot 4}{1\cdot 4}=[/tex]
[tex]\bf\dfrac{15}{4}-\dfrac{4}{4}=[/tex]
[tex]\bf\dfrac{15-4}{4}=[/tex]
[tex]\boxed{\bf\dfrac{11}{4}}[/tex] sau [tex]\boxed{\bf 2\dfrac{3}{4}}[/tex] sau [tex]\boxed{\bf 2,75}}[/tex] ∉ IN
Raspuns: 2,75 nu este numar natural