2 quick algebra questions

[rdf8585]

1. Does y = |x|-5 and y= |2x|-5 have the same domain and/or range?

2. Does y = -x^2+5 and y = -1/2x^2+5 have the same domain and/or range?

Domains and ranges totally befuddle me, and I don't have a graphing calculator, which some people said might help.

 

[Roric]

I could give you the answers, but then you wouldn't know the reasoning behind them, so....

http://www.freemathhelp.com/domain-range.html

You should be able to figure it out from there.

 

[Josh]

An easy and basic way to remember things...

domain: the intervals of the X-axis the equation occupies (how "long" the total graph would go horizontally left and right).

range: the intervals of the Y-axis the equation occupies (how "tall" the total graph would be)

 

[Stinkythe1]

It's amazing how quick you can forget this stuff. I had college algebra 2 years ago and I'm clueless as to how to start on that problem...

Oh well.

 

[swiftaw]

1. Does y = |x|-5 and y= |2x|-5 have the same domain and/or range?

Domain: Whole Real Line, negative infinity to infinity
Range: -5 to infinity


2. Does y = -x^2+5 and y = -1/2x^2+5 have the same domain and/or range?

A little confused by the second equation, is it y = (1/2)x^2 + 5 or y = 1/(2x^2) + 5

For y = -x^2 +5 the domain is the whole real line, and the range is 5 to infinity

For y = (1/2)x^2 + 5 the domain is the whole real line, and the range is 5 to infinity

For y = 1/(2x^2) + 5 the domain is the whole real line except 0, and the range is (5,infinity)