how do you find the domain of the function f(x)=9-x over the square root of x+7

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- Jan 21st 2010, 11:55 AMbastropgarldomain of functions 3
how do you find the domain of the function f(x)=9-x over the square root of x+7

- Jan 21st 2010, 12:26 PMmasters
Hi bastropgarl,

$\displaystyle f(x)=\frac{9-x}{\sqrt{x+7}}$

The denominator cannot = 0. f(x ) would be undefined.

x + 7 cannot be negative within the set of real numbers. You would have the square root of a negative number.

So, x + 7 > 0

Therefore, the domain = {x | x > -7}.