SOLUTION: I'm trying to figure out the domain of this function without a graph. {{{ y=sqrt(2x-8) }}} I tried making it greater than or equal to zero and I ended up with X being less than 4

Algebra ->  Functions -> SOLUTION: I'm trying to figure out the domain of this function without a graph. {{{ y=sqrt(2x-8) }}} I tried making it greater than or equal to zero and I ended up with X being less than 4      Log On


   

Question 778286: I'm trying to figure out the domain of this function without a graph.
+y=sqrt%282x-8%29+ I tried making it greater than or equal to zero and I ended up with X being less than 4. I'm not sure if it was supposed to be less than or greater than. Mostly I'm confused about the process of finding a domain like this.
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
2x-8 ≧ 0

add 8 to both sides

  2x ≧ 8

divide both sides by 2, which is a positive number so you DO NOT
reverse the inequality symbol from ≧ to ≦. You only reverse the 
symbol when you divide by a negative number, NEVER when you divide 
by a positive number.  So it's

   x ≧ 4

Why did you get "less than"?  You must have learned the rule
wrong and thought you reverse the symbol of inequality when you 
divide by a positive.  No, you only reverse it when you divide by
a negative number, but you DO NOT reverse it when you divide by a
positive number.

Edwin