math
posted by Anonymous on .
Consider the following 6 relations on the set of real numbers:
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?

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 = √(102x)
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