domain

Domain is what goes in and Range is what comes out.

\(\displaystyle y=3x+2\). This is a line. So it has a value everywhere.

What can we put in for x and get a real value?. Anything. Therefore, the domain is \(\displaystyle (-\infty, \;\ \infty)\)

See?. The range is then the same.

But, say we had \(\displaystyle \frac{1}{x-1}\). What is the domain?. Everything except 1. That is because when x=1 we have division by 0.

For domain, just think about what x values can be plugged in to get a real result.

Again, say we had \(\displaystyle \sqrt{x-1}\). What can x be?. Everything that gives us a positive inside the radical. The domain is everything except when x<1. Because if x<1, then we have a negative in the radical and that is complex.

Help any?. :D
 
To expand on what Galactus said, the domain of ALL polynomials is the set of Real numbers.

If you know what a polynomial is, then it will help you to memorize the domain fact above. 8-)

3x + 2 is a polynomial.
 
"A polynomial is a mathematical expression involving a sum of powers in one or more variables multiplied by coefficients."
-Wolfram
 
so the range of the fuction y=2x squared,sorry I don't know how to make an exponent on here. haha, it would be 0 or any number above zero,right? It can't be a negative?
 
Kortni said:
y = 2x squared

I don't know how to [type] an exponent We type a caret symbol ^ to show exponentiation.

y = 2x^2

If exponents are more than 1 character, we need to enclose them within grouping symbols (when typing).

y = 2x^(-2)

y = 2x^(C - 1)

[The range] would be 0 or any number above zero, right? Yes. This is correct because squaring any value for x cannot lead to a negative result.

Also, when we talk about numbers that are larger than something, it's better to say "greater than" versus "above".

The Domain is all Real numbers.

The Range is all Real numbers greater than or equal to zero.
Click to expand...
 
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