How to store mathematical symbole(like algebra ) in sql server 2008 ,asp.net , c#

--------------------TABLE-------------------

create table MATH(id int,equation varchar(1000))
insert MATH
select 1,'POWER(x+1,2)' UNION ALL -- (x+1)^2
select 2,'COS(x)' -- Cosinus(x)

--------------------QUERY-------------------

declare @query nvarchar(1000)
declare @Result Float
declare @id int
declare @x float
set @x=0.5
set @id=1
set @query=(select equation from MATH where Id=1)
set @query='select ROUND('+replace(@query,'x',CAST(@x as varchar(50))+'000')+',5)'
exec(@query)
--RESULTS----------------------
--(0.5+1)^2=2.2500
-------------------------------
set @query=(select equation from MATH where Id=2)
set @query='select ROUND('+replace(@query,'x',CAST(@x as varchar(50))+'000')+',5)'
exec(@query)
--RESULTS----------------------
--cos(0.5)=0,87758
-------------------------------