Find Value(s) of x

[nycmathguy]

David Cohen

Let me see if I can at least get started.

y = sqrt{f(x)}

y = sqrt{(x - 1)^2 - 4}

To find the domain, I must set (x - 1)^2 - 4 to be => 0.

Yes?

I found the domain to be
(-infinity, -1] U [3, infinity).

If the domain is correct, what is the next step?

 

[MathLover1]

the domain is correct
To minimize something, we have to take its derivative, set it to 0 and solve for x

 

[nycmathguy]

the domain is correct
To minimize something, we have to take its derivative, set it to 0 and solve for x

Do I take the derivative of f(x) or sqrt{f(x)}?

 

[MathLover1]

sqrt{f(x)}

 

[nycmathguy]

sqrt{f(x)}

d/dx [(x - 1) - 4] = 2(x - 1).

2 (x - 1) = 0

2x - 2 = 0

2x = 2

x = 2/2

x = 1

Yes?

 

[MathLover1]

x = 1

Yes

 

[nycmathguy]

x = 1

Yes

Very cool. A little calculus there.