(6х-9)х(4х+0,4)=0 помогите

Question

(6х-9)х(4х+0,4)=0 помогите

Answer 1

(6х^2 - 9x)(4x+0.4)=0
24x^3+2.4x^2-36x^2-3.6x=0
4x^3-5.6x^2-0.6x=0  /:х
4х^2-5.6x-0.6=0
D=31.36-4*4*(-0.6)=40.96
Х1=-0,1
Х2=1,5