Theorem resqcl

Description: Closure of squaring in reals. (Contributed by NM, 18-Oct-1999)

	Ref	Expression
Assertion	resqcl	$$⊢A\in ℝ\to A^2\in ℝ$$

Proof

Step	Hyp	Ref	Expression
1		2nn0	$$⊢2\in {\mathbb{N}}_0$$
2		reexpcl	$$⊢\left(A\in ℝ\wedge 2\in {\mathbb{N}}_0\right)\to A^2\in ℝ$$
3	1 2	mpan2	$$⊢A\in ℝ\to A^2\in ℝ$$