First, (1)a is greater than -3 and less than or equal to-1. It is actually the solution of the equation. Take A as a constant, and then find X = 3+A, Y =-2A-2, because X is a positive number, that is, X>0, and take X=3+a, that is, 3+A >; 0, y is non-negative, that is, Y & gt=0, brought in,-2a-2 > =0, the solution is -3.

(2) After simplification: bring the formula in at 4 o'clock and think carefully.

Second, the solution: let the distance after 3 kilometers be x meters.

29-8=2 1 yuan

2 1-3 & lt； 3X & lt=2 1

Get 6

The total distance is about 7+3= 10 km.

Haven't you read this chapter yet?