Question

Determinati multimile:

A={x apartine N/ (fractia de mai jos) apartine N}
$\frac{15}{x + 7}$
B={x aparține N/(fractia de mai jos) apartine N
$\frac{12}{2x + 3}$
Cat mai repede daca se poate!

Answer 1

A={x∈N| 15/x+7∈N}

15/x+7∈N

x+7∈D₁₅

x+7∈{1,3,5,15} /-7

x∈{8}

A={8}

B={x∈N| 12/x+3∈N}

12/2x+3∈N

2x+3∈D₁₂

2x+3∈{1,2,3,4,6,12} /-3

2x∈{0,1,3,9} /:2

x∈{0}

B={0}