document.write( "Question 713952: \r
\n" ); document.write( "\n" ); document.write( "F(x)= square root of (x over 4 minus 2) \n" ); document.write( "

Algebra.Com's Answer #438693 by jsmallt9(3758) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"F%28x%29=+sqrt%28x%2F4-2%29\"$
\n" ); document.write( "When asked to find a domain you start by assuming that it is all real numbers. Then you look for x values that need to be excluded. There are certain expressions that cannot be allowed in Math and any value for x that creates such an expression must be excluded from the domain.

\n" ); document.write( "Some of the more common expressions that must be avoided:

Zero denominators (since division by zero is undefined)
Negative radicands of even-numbered roots. (\"Radicand\" is the name for the expression within a radical. Even-numbered roots are square (2nd) roots, 4th roots, 6th roots, etc.) These must be avoided because you can't raise any real number to an even power and get a negative result.
Invalid arguments or bases of logarithms. (Valid arguments are positive. Valid bases are positive but not 1.

Our function has no logarithms. It does have a denominator. But it is a 4. And no matter what value x has, the denominator will always be 4, never zero.

\n" ); document.write( "Our function does have an even-numbered root, a square root. So we must make sure that x would never have a value that would make the radicand negative. Instead of thinking that x can't make the radicand negative it is easier to that we want x to make the radicand positive or zero. So we write a mathemtical sentence that says the radicand, $\"x%2F4-2\"$ , is greater than or equal to zero:
\n" ); document.write( " $\"x%2F4-2%3E=0\"$
\n" ); document.write( "Solving for x...
\n" ); document.write( "Adding 2:
\n" ); document.write( " $\"x%2F4%3E=2\"$
\n" ); document.write( "Multiplying by 4:
\n" ); document.write( " $\"x%3E=8\"$
\n" ); document.write( "These are the values we want x to be. This is the domain of F(x): All numbers greater than or equal to 8. \n" ); document.write( "

\n" );