Question

Answer 1

a.

\(\exists x\in\mathbb{R}: x^2\leq 0\)

b.

\(\forall x\in\mathbb{R}: x\leq x^2\)

c.

\(\forall x\in\mathbb{Q}: 4x^2-1\neq 0\)

d.

\(\exists x\in\mathbb{R}: x^2-x+7\leq 0\)

e.

\(\exists x\in\mathbb{R}: x^2-x-2\geq 0\)

Answer 2

f.

\(\forall x\in\mathbb{R}: x^2\neq 3\)

g.

\(\exists x\in\mathbb{N}: n^2+1\vdots 3\)

h.

\(\exists n\in\mathbb{N}: n^2+2n+5\) là hợp số 

i.

\(\exists n\in\mathbb{N}: n^2+n \) lẻ

k.

\(\exists n\in\mathbb{N}: n^2-1\) chẵn