点a b在数轴上分别表示实数a b,AB之间的距离表示为|AB|
1个回答

4)

该函数与 x 轴交点 A(x1,0),B (x2,0)

|AB|= x2 - x1 = 6

x2 + x1 = -b/a = 2

x2 = (6+2)/2 = 4,x1 = (2-6)/2 = -2

A (-2,0),B (4,0)

5)

当 x > 2 时,|x+1| + |x-2| = x + 1 + x - 2 = 2x -1 > 3

当 x < -1 时,|x+1| + |x-2| = -x - 1 - (x - 2) = -2x + 1 >3

当 -1