the graph of the function ( f(x)=(x + 2)(x + 6) ) is shown below. what is true about the domain and range of…

the graph of the function ( f(x)=(x + 2)(x + 6) ) is shown below. what is true about the domain and range of the function? the domain is all real numbers, and the range is all real numbers greater than or equal to -4. the domain is all real numbers greater than or equal to -4, and the range is all real numbers. the domain is all real numbers such that ( -6leq xleq -2 ), and the range is all real numbers greater than or equal to -4. the domain is all real numbers greater than or equal to -4, and the range is all real numbers such that ( -6leq xleq -2 ).
Answer
Explanation:
Step1: Analyze the domain of a quadratic function
For any quadratic function (y = ax^{2}+bx + c) (in this case (f(x)=(x + 2)(x + 6)=x^{2}+8x + 12)), the domain is all real numbers because there are no restrictions on the values of (x) for which the function is defined.
Step2: Find the vertex of the parabola (to determine the range)
The (x) - coordinate of the vertex of a parabola (y=ax^{2}+bx + c) is given by (x=-\frac{b}{2a}). Here (a = 1), (b = 8), so (x=-\frac{8}{2\times1}=-4). Substitute (x=-4) into the function (f(x)=(x + 2)(x + 6)): (f(-4)=(-4 + 2)(-4+6)=(-2)\times2=-4). Since (a = 1>0), the parabola opens upwards. So the minimum value of the function is (y=-4). The range of the function (y) (or (f(x))) is (y\geq - 4).
Answer:
The domain is all real numbers, and the range is all real numbers greater than or equal to (-4).