Answer:
C. -4/3
Explanation:
Start by finding the roots of the equation by factorising.
3x³+4x²-4x=0
x(3x²+4x-4)=0
x(3x-2)(x+2)=0 [because (ax+b)(cx+d)=(ac)x²+(ad+bc)x+(bd)]
If multiplying these three terms works out to be zero, we know that one of the terms must be zero, as anything multiplied by zero is zero.
So
x=0, or 3x-2=0, or x+2=0
Which means our roots are
x=0, x=2/3, x=-2
Now find the sum of these roots: 0+(2/3)-2=(2/3)-(6/3)=-4/3