How do you find the domain of $f (x) = x^{3} - 8 x + 4$ $f(x)=x^3-8x+4$ ?

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Answer 1 · 2018-06-14T19:14:27

$x inRR$

We're dealing with a polynomial here, which is defined for all real numbers. Let's think for a moment:

Are there any values of $x$ that will make my function undefined?

Let's plug in some values for $x$ :

$f(3)=(3)^3-8(3)+4=color(blue)(7)$

$f(11)=(11)^3-8(11)+4=color(blue)(1247)$

$f(41)=(41)^3-8(41)+4=color(blue)(68597)$

Notice, I could have picked much more ridiculous values for $x$ , but we see that it is defined for all real numbers. We can say

$x inRR$

Hope this helps!

How do you find the domain of f(x)=x^3-8x+4f(x)=x3−8x+4f(x)=x^3-8x+4?