Question

The function f(x) = (x - 4)(x - 2) is shown.

What is the range of the function?
o all real numbers less than or equal to 3
o all real numbers less than or equal to -1
O all real numbers greater than or equal to 3
O all real numbers greater than or equal to -1
2
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-1028
-2​

Answer 1

all real numbers greater than or equal to -1

Explanation:

In order to solve this problem we need to know the vertex and the direction its pointing.

First we expand,

x^2-6x+8

To find the x value of the vertex we use this formula (-b/2a).

-(-6)/2(1) = 3

Now we plug 3 in the equation to get the y value,

(3)^2 - 6(3) + 8 = 9 - 18 + 8 = -1

The vertex is (3,-1)

We know the graph points up because x^2 is positive

The vertex is the lowest point, so we now know that -1 is the starting range and if the graph is pointing up, that means all values greater than -1.

This leads to our answer all real numbers greater than or equal to -1.