Factor 5x^4+35x^3+60x^2=0

5x^4+35x^3+60x^2=0
5x²(x² + 7x + 12)=0
5x²(x+3)(x+4)=0
5x²= 0 or x+3= 0 or x+4=0
x=0 or x= -3 or x=-4

5x^4+35x^3+60x^2=0
5x^2(x^2+7x+12)=0
5x^2(x+4)(x+3)=0
hence x=0 or x= -4 or x= -3