Posted by **Milia** on Sunday, June 5, 2011 at 5:35am.

How would you tell if an equation is a funtion or not. I know that it has to have only one y-value for every x...but how do you identify this in an equation (rather than a graph)

ie. y=1/2x-7 (how do i tell if this is a funtion or not)?

Any help would be much appreciated :)

- Math -
**Andy**, Sunday, June 5, 2011 at 6:28am
when dealing with linear functions, the general formula is y= mx + c..where m is the gradient and c is the y-intercept. To find the value of x simply make y = to zero.hence the equation(y=1/2-7) is a linear function because if substituted in the general formula,1/2 would be the gradient(since it is the value/coefficient of x),, c=-7 and x=-1.

- Math -
**drwls**, Sunday, June 5, 2011 at 6:28am
Please use parentheses where needed for clarity. I don't know if that is

1/(2x-7) or (x/2) -7 or (1/2x) -7

In each case, y is clearly a function of x because there is one and only one y for each x. (Except possibly where a denominator vanishes)

- Math -
**Milia**, Sunday, June 5, 2011 at 6:40am
thanks :)

## Answer This Question

## Related Questions

- math,help - I definately do not understand this problem. If y varies directly ...
- Algebra - For what value(s) of b will x^2 + bx + 3 have exactly one root? I'm ...
- math - How do I know that x^2-7=y is a function? thanks you know its a function ...
- CountIblis, can i bother you - Countiblis, i know that you might be busy do you ...
- Math 117 Algebra - for the following equation, state the value of the ...
- Math - How is an inequality different from an equation? Give a real-world ...
- Algebra 2 - I am creating a project for math in which I have to draw an object ...
- Algebra - Here's the question I'm having trouble with: Tell how you would ...
- 9th grade - What is the value of c in the equation f(c)=0 with the funtion f(x)=...
- math check again please - I have a slope of -3/4 and the y-intercept at 8 the ...

More Related Questions