The equation of a circle is x2+y2=16.

The radius of the circle is

4

Step-by-step explanation:

the standard equation of a circle will be given in the form of

, where r is the radius and (x1, y1) is the center point of the circle

in this situations r^2 = 16

r = +4 or -4, but since length cannot be negative, r = 4

4

Step-by-step explanation:

from the circle equation ( x - h )^2 + ( y - k )^2 = r^2, 16 is the radius squared, so x^2=16

x= 4 x=-4

we reject -4, bc it's negative, and a radius cannot be negative,

r=4

b.an increase in a causes b to decrease

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value