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

Question

A) y=2x−5,

B) x2+y2=1,

C) x=20−2y,

D) y=10−x2−−−−−−√,

E) y=2x2−3x+4 and

F) y=|x|
How many of these relations define y as a function of x in the domain −10≤x≤10?

Answer 1

A , C, and F are linear, thus defined for all x's

B)
x^2 + y^2 = 1 is a circle , thus not a function, which is only defined for -1 ≤ x ≤ +1

E) a quadratic function, defined for all x's

D) not sure what you meant here
if it is y = √(10-2x)
then it would be defined only for
10 - 2x ≥ 0
-2x ≥ -10
x ≤ 5
so no, not defined for all of -10 ≤ x ≤ 10

So all would be except B and D