Content mathml - partial diffs, ranges

Hello,
 I have some questions about content MathML.

How would you write  the following equations in content MathML?:

1) 

E = 10-200 keV

(energy E is in range 10 to 200 keV)



2) 

 / dy \	      / dz \
|  --  |   = |  --  |
 \ dx / z     \ dx / y

ie.: dy/dx when z is constant 
is equal to 
dz/dx when y is constant.

BTW.: how to express in content MathML, that
"x" is constant?


Thank you very much for your suggestions.

Regards
Jiri Jirat



-- 
Jiri Jirat
ZVON.org