If the function is -x^2 -4x + 2 (you skipped the operator between -4x and 2), then:
1) The domain is all the real numbers (-infinity, + infinity)
2) The range is all the real numbers below 6, given that the vertex is (2,6) and the function opens down (because the coefficient of x^2 is negative).
3) The function increases over the interval (-infinity, 2) and decreases over the interval (2,+infinity).
4) The y-intercept is the value of the function when x =0, so it is 2 (positive).
Then, the only true statement is that the range is y such that y is 6 or below