Question

Given that D(x) = 2x, select all of the following that are true statements.

D(x) is a function.
x is the dependent variable.
D(6) = 3
D(x) is a direct variation.
D(x) is a rule for the set of points (5, 10), (6, 12) and (-2, -4).

Answer 1

When you have things like f(x), that means its function, D(x) is in functional notation, so it's a function.
Would you say it's dependent...?
D(3) = 2(3) = ?
Is it a direct variation, think about the relation between x and D(x) what happens between them, kind of obvious.
The last one you just have to plug in the values and D(x) will be treated as the y - output, so D(5) = 2(5) = 10, so the first point is right, do the rest.