SOLUTION: State the domain of the following and provide a brief explanation of the answer. m(x)=5/x^2-9 l(x)=5x-4 g(x)=7x=4/x=4

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Question 202423: State the domain of the following and provide a brief explanation of the answer.
m(x)=5/x^2-9
l(x)=5x-4
g(x)=7x=4/x=4

Found 2 solutions by dyakobovitch, jsmallt9:
Answer by dyakobovitch(40)   (Show Source): You can put this solution on YOUR website!
To find the domain of a function, it is most appropriate to create a graph. Domain satisfies the bounds for the x-axis, or the horizontal movement of the graph.
M(x)=5/x^2 - 9 is a rational function with the following graph: , so the domain is (-∞,∞).
L(x)=5x-4 is a linear equation with the graph: . As seen in the graph, it is a line that has no bounds in the Cartesian Coordinate plane.
Its domain is (-∞,∞).
G(x)=7x=4/x=4. If you can clarify the equation I can help you, but this is clearly not a function since there are three equal signs.

Answer by jsmallt9(3758)   (Show Source): You can put this solution on YOUR website!
The domain of a function is the set of all possible values for the input variable, which is usually "x". Generally, when a domain is not explcitly defined, the domain of a function is all Real numbers. However, one must exclude values which cause expressions which cannot be allowed.

Examples of expressions which cannot be allowed:
Now let's apply this to your problems.


Since we have a denominator we must avoid x-values that would make the denominator zero. So if we solve we will find the x-values we must exclude from the domain. Factoring this equation we get . From this we can see that the solution is x = 3 or x = -3.
So the domain of m(x) is all real numbers except 3 and -3.

l(x)=5x-4
Since none of the items described above (denominators, even-numbered roots, logarithms, etc.) are present, there is nothing to exclude. The domain is all Real numbers.

g(x)=7x=4/x=4
With 3 equal signs I'm not sure what this is. Since the "=" and the "+" are on the same key, I'm going to assume that the last two "=" are supposed to be "+".
If we must make sure the denominator of x does not become zero. So we must exclude 0 from the domain.
If instead then we must make sure (x + 4) is not zero. So x must not be -4.

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