Find all values of f(x) for which f(x) `=x+sqrt(x^2)`

Answer

`[0,oo)`

Explanation

`f(x+sqrt(x^(2))=x+|x|`
`={(x+x",",x ge0),(x-x",",x lt 0):}`
`={(2x",",x ge0),(0",",x lt 0):}`
Hence, f(x) takes values `[0,oo)`