How to propertly format "Δ𝑥" using MathML?

Question

I'm using MathML embedded in HTML to put mathematical expressions in an HTML document. I'm having difficulty with properly formatting mathematical expressions containing "Δ𝑥". The MathML expressions

<math>
  <mrow>
    <mi mathvariant="normal">&Delta;</mi>
    <mi>x</mi>
  </mrow>
</math>

and

<math>
  <mrow>
    <mo>&Delta;</mo>
    <mi>x</mi>
  </mrow>
</math>

each yield "Δ 𝑥" (i.e. with space between "Δ" and "𝑥"), while

<math>
  <mi>&Delta;x</mi>
</math>

yields "Δx" (i.e. "x" isn't italicized).

Is there a generally accepted way to properly format "Δ𝑥" using MathML?

Answer 1

Another solution, the MathML expression

<math>
  <mi>&Delta;&#x1D465;</mi>
</math>

yields "Δ𝑥".

Note that 𝑥 is an HTML entity for the "mathematical italic small x" character.