14, because the two square roots of a positive number are in opposite directions.

So a+3=-(2a- 15)

The solution is a=4, a+3=7, 2a- 15=-7, so this number =7? =49

15 because 3 < √ 10 < 4.

So b-√10 =-(√10-b) =-3.

9. Calculate the vertical section of the point to the straight line according to the distance from the point to the straight line (the vertical section is the shortest).

Because 2 < 4 < 5

So the distance from point P to line L is less than or equal to 2? That is, no more than 2

So choose: C.

Please adopt it. Thank you.