How do you find the domain and range of sqrt(25-(x-2)^2) +3?

1 Answer
Jan 30, 2017

The domain is x in [-3,7]
The range is y in [3,8]

Explanation:

Let g(x)=sqrt(25-(x-2)^2)+3

What is under the sqrt sign is >=0. this is the domain

So,

25-(x-2)^2>=0

25-(x^2-4x+4)>=0

x^2-4x+4-25<=0

x^2-4x-21<=0

Let's factorise

(x-7)(x+3)<=0

Let f(x)=(x-7)(x+3)

Let 's do a sign chart to solve this inequality

color(white)(aaaa)xcolor(white)(aaaa)-oocolor(white)(aaaa)-3color(white)(aaaa)7color(white)(aaaa)+oo

color(white)(aaaa)x+3color(white)(aaaaa)-color(white)(aaaa)+color(white)(aaaa)-

color(white)(aaaa)x-7color(white)(aaaaa)-color(white)(aaaa)-color(white)(aaaa)-

color(white)(aaaa)f(x)color(white)(aaaaaa)+color(white)(aaaa)-color(white)(aaaa)+

Therefore,

f(x)<=0 when x in [-3,7], this is the domain

To calculate the range,

When x=-3, =>, g(-3)=3

When x=7, =>, g(7)=3

When x=2, =>, g(2)=8

Let y=sqrt(25-(x-2)^2)+3

The range is y in [3,8]

graph{(sqrt(25-(x-2)^2)+3) [-9.74, 12.76, -2.055, 9.195]}