ve must factor
factor by grouping
hmm
erm
(trial and error)
if we group it like this:
(-3x^2-6x)+(x^3+8)
we can factor each group
the first is a -3x
the 2nd is a sum of 2 perfect cubes
(-3x)(x+2)+(x+2)(x²-2x+4)
undistribute (x+2) from each
(x+2)(-3x+x²-2x+4)
(x+2)(x²-5x+4)
can we factor more?
what 2 numbers multiply to get 4 and add to get -5?, -1 and -4
(x+2)(x-1)(x-4)
set eqch to zero (assuming it is equal to 0)
0=(x+2)(x-1)(x-4)
0=x+2
-2=x
0=x-1
1=x
0=x-4
x=4
x=-2, 1, 4