Which of the points is closer to the plane - is this right?

[Damascus Road]

I have two points, P(0,0,0) and Q(-1,-2,0)

and a plane x + 7y - 15z = 30

May I simply:

$$\sqrt{(1-0)^{2} + (7-0)^{2} + (-15-0)^{2}}$$

$$\sqrt{(1+1)^{2} + (7+2)^{2} + (15-0)^{2}}$$

and the one with the lesser magnitude is closer?

 

[Damascus Road]

Nevermind.