# Possible Functions

Algebra Level 2

Consider the following $$6$$ relations on the set of real numbers:

A) $$y = 2x - 5$$,

B) $$x^2 + y^2 =1$$,

C) $$x = 20-\frac{2}{y}$$,

D) $$y = \sqrt{10 - x^2}$$,

E) $$y = 2x^2-3x+4$$ and

F) $$y = |x|$$

How many of these relations define $$y$$ as a function of $$x$$ in the domain $$-10\leq x \leq 10$$?

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