Answer
Solutions:
$x=0$
$x=-3$
Work Step by Step
$5x^3+30x^2+45x=0$
$5x(x^2+6x+9)=0$
$5x[x^2+2(3)x+3^2]=0$
$5x(x+3)^2=0$
$5x=0$
$x=0$
or
$(x+3)^2=0$
$x+3=0$
$x=-3$
Check the solutions:
$x=0$:
$5(0)^3+30(0)^2+45(0)=0+0+0=0$
$x=-3$:
$5(-3)^3+30(-3)^2+45(-3)=5(-27)+30(9)-135=-135+270-135=0$
