The seventh question, knowledge point: the second grade algebra-the nature of real numbers.

Solution: According to the definition of arithmetic square root, a-2007≥0.

Therefore, a≥2007.

|2006-a|=a-2006

The original equation is: a-2006+√ (a-2007) = a.

Get: √(a-2007)=2006

a-2007=2006？

So a-2006? =2007