How do i do 9 and 10?
if you can, write the steps too and

Y = 3x^2 + 6x -2
y = 3(x^2 + 2x ) - 2    complete the square on the x^2 + 2x.
y = 3(x^2 + 2x + 1) -2-3
y = 3(x+1)^2 -5        vertex is (-1, -5); AOS is x = -1; opens upward

y = x^2 + 9x + (81/4) this will factor
y = (x + 9/2)^2          vertex is (-9/2, 0); AOS is x = -9/2; opens upward

The density of the cube is 40