2y/5y cube + 4y square + 6y

here down is the answer

(2y/5y) ^3+4y^2+6y

8y^3/125y^3 + 16y^2+6y

8/125+16y^2+6y

8/125+16y^2+6y=0

16y^2+6y+8/125=0

it is in the form of quadratic equation

formula:

x = (-b+-square root of b^2-4ac) / 2a

here a=16, b=6&c=8/125

x = (-b+-square root of b^2-4ac) / 2a

x = (-6+-square root of 36-4.09) / 2a here 4.09 came by calculation

x = (-6+-31.91) / 2

so

x = (-6+31.91) / 2 first (+);

x=25.91/2

x=12.955;

x = (-6-31.91) / 2 then (-);

x=-37.91/2

x=-18.955;

ans is = 12.955&-18.955;