inserting plain text without converting to html entities

[reza1370programmer]

hi everyone
i am using some mathml tags inside the ngx-editor like this
<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>2</mn><mn>5</mn></mfrac></math>
as you see there are some special characters inside mathml codes that i dont want to convert to html entites because this mathml code will render by mathjax later
how can i insert this as plain text?
any help will highly appreciated