Answer:
a. The domain is x = 20
Step-by-step explanation:
If f(x)=20, it means that ALL values of x will equal 20
f (1) = 20
f (2) = 20
f (100) = 20
So, no matter what the x value, the y value will always be 20.
The domain of a function is the range/span/numbers possible of x values, the range of a function is the range/span/numbers possible of y values.
[I remember which is which alphabetically; d is before r , and x is before y]
So, we know that the entire span/range/numbers possible for y are 20. Because no matter what we put for x, this function is always 20 for y.
Now, the span/range/numbers possible for x is -∞ to +∞
Any number, 1, 5, -100000, are all possible x values that you could put into the equation.
So we know that the domain of the function is (-∞, ∞)
Meaning that the domain is not x = 20
c) [The graph of the function is a straight line because all x values have the corresponding y-value of 20. So, the graph looks like a straight, horizontal line across 20 that goes on for infinity]
d) [The domain includes (-∞ , +∞) meaning that it includes negative infinity to positive infinity. This means that the domain is all real numbers.]
{by the way, I am using () to mark the domain because I am writing about infinity. A ( parentheses ) does not include that value itself, and a [bracket] does. Because we cannot ever reach infinity, it is marked with a ( ) because it is not even possible to include the value of infinity.}
