Liberal arts: 4; three

Is it literature or reason?

In this paper, the coordinates of point A and the origin are directly substituted into the formula of D.

The second null can be solved by absolute value attribute.

| x- 1 |+| x+2 | = | 1-x |+| 2+x | >； =|( 1-x)+(2+x)|=3

Or use a piecewise function. d(M，B)= | x- 1 |+| y | = |(x- 1)+(2+x)| =-2x- 1(x & lt； =-2); 3(-2 & lt； x & lt= 1); 2x+ 1(x & gt； 1)

On this basis, the function image is drawn, which is an image in which X decreases from negative infinity to -2, from -2 to 1 is a line segment with y=3, and from 1 to positive infinity. The known minimum value is 3.

Manage the first empty text.

The second space: you can use drawing analysis to score k>= 1 and 0.

Or discuss the different situations of | x- 1 | | kx+k+3 | and draw the image of piecewise function.

I hope this answer is helpful to you.