Domain of Radical Expression...1

[nycmathguy]

Section 2.7
Question 72

Set radicand to be ≥ 0.

x^2 - 9 ≥ 0

(x - 3) (x + 3) ≥ 0

x - 3 ≥ 0

x ≥ 3

x + 3 ≥ 0

x ≥ -3.

Domain: (-infinity, -3] U [3, infinity)

You say?

 

[MathLover1]

same mistake here, set x^2 - 9 =0

 

[nycmathguy]

same mistake here, set x^2 - 9 =0

 

[MathLover1]

I didn't pay good attention what is given, and I was thinking you are givenx^2 - 9
actually you are given sqrt(x^2 - 9)-> so, your domain is correct

 

[nycmathguy]

I didn't pay good attention what is given, and I was thinking you are givenx^2 - 9
actually you are given sqrt(x^2 - 9)-> so, your domain is correct

Very good. We all make mistakes.