document.write( "Question 75570This question is from textbook
\n" ); document.write( ": It says \"find f(x)=0\" what does it mean?\r
\n" ); document.write( "\n" ); document.write( "The porblem:\r
\n" ); document.write( "\n" ); document.write( "f(x)=3x-12 \n" ); document.write( "

Algebra.Com's Answer #54214 by jim_thompson5910(35256) $\"\"$ $\"About$

You can put this solution on YOUR website!
Since we're looking for f(x)=0, we're looking for y=0 since y and f(x) can be interchanged. In other words, we are looking for the x-intercept, since y=0 for all x-intercepts. So we substitute 0 in for f(x) and we get:\r
\n" ); document.write( "\n" ); document.write( " $\"0=3x-12\"$ Now we solve for x
\n" ); document.write( " $\"0%2B12=3x%2Bcross%28-12%2B12%29\"$ Add 12 to both sides
\n" ); document.write( " $\"12%2F3=cross%283%2F3%29x\"$ Divide both sides by 3. This will isolate x.
\n" ); document.write( " $\"x=4\"$ \r
\n" ); document.write( "\n" ); document.write( "So if we let x=4 we should get f(x)=0, in other words, f(4)=0. So lets verify this:\r
\n" ); document.write( "\n" ); document.write( "

\n" ); document.write( "Check:
\n" ); document.write( " $\"f%28x%29=3x-12\"$
\n" ); document.write( " $\"f%284%29=3%284%29-12\"$ Plug in x=4
\n" ); document.write( " $\"f%284%29=12-12\"$
\n" ); document.write( " $\"f%284%29=0\"$ works
\n" ); document.write( "This verifies our answer
\n" ); document.write( " $\"+graph%28+300%2C+200%2C+-6%2C+5%2C+-10%2C+10%2C+3x-12%29+\"$ Here you can see the graph of $\"y=3x-12\"$ and the x-intercept of (4,0) \n" ); document.write( "

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