Chasuble. Not at all. The sprinkling, and, indeed, the immersion of adults is a perfectly canonical practice

2x^3+8x^2-3x-12=0

2x^2(x+4)-3(x+4)=0

(x+4)(2x^2-3)=0

x1=-4

x2=0

x3=1.5 

2x^3+8x^2-=0

(2x^3+8x^2)-(3x-12)=0

2х^2(х+4)-3(х-4)=0

(х+4)*(2х+3)=0

Х+4=0 или 2х+3=0

х=0-4        2х=0-3

х=-4          2х=-3

                 х=-1,5

ответ:-4; -1,5.