contestada

The perfect squares,1,4,9,16,25,...... are closed under
(A)addition (b) multiplication (c) square-rooting (d) none of these

Respuesta :

DeanR
The perfect squares are closed under (b) multiplication.

We see 1+4=5, not a perfect square, not not closed under addition.

We see [tex]\sqrt{4}=2,[/tex] not a perfect square, so ...

But 

[tex]a^2 \times b^2 = (ab)^2[/tex]

a perfect square