How to find the linear equation with the distance of root sign 5 / 5 from the line 2x + y = 0?

How to find the linear equation with the distance of root sign 5 / 5 from the line 2x + y = 0?

Firstly, a line √ 5 / 5 away from the line 2x + y = 0 must be parallel to the line 2x + y = 0, which can be set as the line 2x + y + C = 0. Then, according to the distance formula d = | C1-C2 | / √ (A & # 178; + B & # 178;), we know that the parameter C of the obtained line satisfies | C | = 1, that is, C = 1 or C = - 1, so the obtained line is a line 2x