(6y+15)(2,4-0,8y)=0 помогите

Question

(6y+15)(2,4-0,8y)=0 помогите

Answer 1

14,4у-4,8у^2+36-12у=0
-4,8у^2-2,4у+36=0 |:(-2,4)
2у^2+у-15=0
D=b^2-4ac=1^2*4*2*(-15)=
=1+120=121
Y=-1+11/4=2,5
Y=-1-11/4=-3