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Mathematics 22 Online
OpenStudy (imterribleatmath):

will give medal for anwser.

OpenStudy (eliesaab):

What is f(g(x))?

OpenStudy (eliesaab):

\[ f(g(x)) =\sqrt{8(x-3)} \]

OpenStudy (eliesaab):

When is the square root defined? Can you take \(\sqrt {-5}\) as a real number?

OpenStudy (eliesaab):

Are you with me?

OpenStudy (imterribleatmath):

i just do not understand

OpenStudy (eliesaab):

To be able to take the square root of a number, this number must be positive or zero. Do you know that?

OpenStudy (imterribleatmath):

i did not.

OpenStudy (eliesaab):

Do now

OpenStudy (eliesaab):

For example \[ \sqrt{25}=5 \] but \[ \sqrt{-25} \] is not a real number and is therefore not defined as such

OpenStudy (imterribleatmath):

ok got it

OpenStudy (eliesaab):

What is under the square root in your composed function \[ f(g(x))=\sqrt{ 8(x-3)} \] ?

OpenStudy (eliesaab):

What is under the square root is \[ 8(x-3) \] this quantity must be \( \ge 0\)

OpenStudy (eliesaab):

What values of x will do that?

OpenStudy (imterribleatmath):

do i solve for x?

OpenStudy (eliesaab):

\[ (x-3)\ge 0\\ x\ge 3 \]

OpenStudy (eliesaab):

So the domain is \[ [3, \infty[ \]

OpenStudy (eliesaab):

What is the smallest number in this interval?

OpenStudy (imterribleatmath):

wouldnt it be 3?

OpenStudy (eliesaab):

Yes

OpenStudy (eliesaab):

So what is the answer?

OpenStudy (imterribleatmath):

is it 3? how would i find out the smallest number

OpenStudy (eliesaab):

Yes it is 3. If the numbers you are dealing with are 3 and all the numbers bigger than 3. What would be the smaller one?

OpenStudy (imterribleatmath):

the 3

OpenStudy (imterribleatmath):

so the smallest number in the domain is 3 ?

OpenStudy (imterribleatmath):

was correct thanks

OpenStudy (eliesaab):

yes

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