`(1)/(sqrt(7-6x-x^(2)))`

Explanation

`int(1)/(sqrt(7-6x-x^(2)))`
`=int(1)/(sqrt(7-(x^(2)+6x)))dx`
`=int(1)/(sqrt(16-(x^(2)+6x+9)))dx`
`=int(1)/(sqrt(4^(x)-(x+3)^(2)))dx`
`=sin^(-1)((x+3)/(4))+c`