Question 335377
20y^3+5y^2-15y 
solution :

20y^3 +5y^2-15y
 here  5y is common
so the equation becomes
5y(4y^2+y-3)
now you have to factor
4y^2+y-3 =4y^2+4y-3y-3
         4y(y+1)-3(y+1)

(4y-3)(y+1)
20y^3 +5y^2-15y =5y(4y-3)(y+1)