Positive and Negative Domains: Comparisons to zero or between parabolas

The following function is graphed below:

$f(x)=-2x^2+4x-6$

For which values of x is
f(x)<0 true?

For all values of x

The following function is graphed below:

$y=x^2-6x+8$

For which values of x is

f(x)>0 true?

2 < x , x < 4

The following function is graphed below:

$f(x)=-2x^2+4x-6$

For which values of x is

f(x)>0 true?

No answer

The following function is graphed below:

$y=x^2-6x+8$

For which values of x is

f(x)<0 true?

2 < x < 4

The following function is graphed below:

$y=-x^2+5x+6$

For which values of x is

f(x)>0 true?

-1 < x < 6

The following function is graphed below:

$y=-x^2+5x+6$

For which values of x is

f(x)<0 true?

Answers (a) and (b)