`sqrt(1-4x-x^(2))`

Explanation

`I=intsqrt(1-4x-x^(2))dx`
`=intsqrt(-(x^(2)+4x-1-2^(2)+2^(2))dx`
`=intsqrt(-[(x+2)^(2)-(sqrt5)^(2)])dx`
`=intsqrt((sqrt5)^(2)-(x+2)^(2))dx`
`rArr" "I=(x+2)/(2)sqrt(1-4x-x^(2))+(5)/(2)sin^(-1).((x+2))/(sqrt5)+C`