Question

$a = \sqrt{2 - 2} \\ b = \sqrt{2 + 2}$
Aratati ca b supra a - √2 apartine Q

VA ROG MULT

Answer 1

$a = \sqrt{2-2} =\sqrt0 = 0\\ \\ b = \sqrt{2+2} = \sqrt4 = 2 \\ \\ \dfrac{b}{a-\sqrt2} = \dfrac{2}{0-\sqrt2} = \dfrac{2}{-\sqrt2} = -\dfrac{2}{\sqrt2} = \\ \\ = -\dfrac{2\sqrt2}{\sqrt2\cdot\sqrt2} = - \dfrac{2\sqrt2}{2} = -\sqrt2 \notin \mathbb_{Q}$
Enuntul probabil probabil este scris gresit. Acea expresie nu apartine lui Q.