Which is the largest interval over which the function shown in the table is decreasing?

Question

x f(x)=3x^2 (x,y)

-2 12 (-2,12)

-1 3 (-1,3)

0 0 (0,0)

1 3 (1,3)

2 12 (2,12)

x<-1 or

x<0 or

x>0 or

x>3

Answer 1

for x<0 f(x) is decreasing, f'(x)<0

it's an upward opening parabola. with vertex = (0,0)

it's decreasing to the left of the vertex, when x<0