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If f(x) = x+7 and g(x) = x=13, what is the domain of (fºg)(x)?

If f(x) = x+7 and g(x) = x=13, what is the domain of (fºg)(x)?-example-1
User Jan Zich
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1 Answer

5 votes

Answer:

The domain is {x I x ≠ 13} ⇒ the last answer

Explanation:

* Lets talk about the composite function

- It is a function is found from two given functions by applying one

function into the second function.

- The applying function is the domain of the second function

- (f °g)(x) means g(x) is applying into f(x)

* Lets solve the problem

∵ f(x) = x + 7

∵ g(x) = 1/(x -13)

- To apply g(x) into f(x) replace x in f(x) by g(x)

∴ f(g(x)) = f(1/(x - 13)) = 1/(x - 13) + 7

- The domain of the function is all values of x which make the function

defined

- The domain is all real numbers except the value which makes

the denominator = 0

- To find this value put the denominator = 0

∵ The nominator of (f ° g)(x) is x - 13

∴ Put x - 13 = 0

∴ x - 13 = 0 ⇒ add 13 to both sides

∴ x = 13

∴ The domain of (f ° g)(x) is all real numbers except x = 13

* The domain is {x I x ≠ 13}

User Nikolay Ermakov
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6.2k points