$13 \cdot 22$ The product of the largest and smallest roots of the equation $x|x|-5|x|+6=0$ is
(A) -6 .
(B) 3 .
(C) -3 .
(D) 6 .
(E) -8 .
(China Hubei Province Wuhan City Junior High School Mathematics Competition, 1985)
[Solution] When $x \geqslant 0$, the equation becomes $x^{2}-5 x+6=0$, solving this yields
$$
x_{1}=2, \quad x_{2}=3 .
$$

When $x<0$, the equation becomes $-x^{2}+5 x+6=0$, solving this yields
$x_{3}=-1, x_{4}=6$ (discard as it does not meet the condition).

Thus, the maximum root of the equation is 3, the minimum root is -1, and their product is -3. Therefore, the answer is $(C)$.