Is the semantic tags example correct in https://www.w3.org/Math/whatIsMathML.html?

I'm a newbie in MathML, so sorry if my question seems stupid.

I started to read MathML intro and I bumped into this page:
https://www.w3.org/Math/whatIsMathML.html

At the end of this page, there's an example for the math expression
x² + 4x + 4 = 0

But when I read the semantic tags example, I only get
x² + 4x + 4
and the "= 0" seems missing for me.

Could someone tell me if the example is correct or not?

Thanks in advance