document.write( "Question 692859: The solution for x-7<-12 is x<-5 . My text book recommends checking the solution by substituting -5 into the equation x-7=-12 to see if -5 is the correct boundary point, if -12=-12 then -5 is the correct boundary point.\r
\n" ); document.write( "\n" ); document.write( "My question is this, why & where does the idea of plugging in -5 into x-7=-12 to see if it's the correct endpoint or boundary point come from? What does the equation have to do with the inequality???\r
\n" ); document.write( "\n" ); document.write( "Thanks
\n" ); document.write( "Ralph \n" ); document.write( "

Algebra.Com's Answer #427121 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Since you get $\"+x+%3C+-5+\"$ , my method is to
\n" ); document.write( "check by saying $\"+x+=+-5.001+\"$
\n" ); document.write( " $\"+x+-+7+%3C+-12+\"$
\n" ); document.write( " $\"+-5.001+-+7+%3C+-12+\"$
\n" ); document.write( " $\"+-12.001+%3C+-12+\"$
\n" ); document.write( "This is true
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\n" ); document.write( "What they say is \" For what value of $\"+x+\"$ does
\n" ); document.write( "the inequality begin to fail ?\"
\n" ); document.write( "They could have said it fails for
\n" ); document.write( " $\"+x+%3C+-4.999+\"$ , but it also fails for
\n" ); document.write( " $\"+x+%3C+-4.9999+\"$ , and also for
\n" ); document.write( " $\"+x+%3C+-4.99999+\"$
\n" ); document.write( "This approaches $\"+x+=+-5+\"$
\n" ); document.write( "-------------------------
\n" ); document.write( "Also, they could say the inequality passes for
\n" ); document.write( " $\"+x+%3E+-5.001+\"$ , but also for
\n" ); document.write( " $\"+x+%3E+-5.0001+\"$ also for
\n" ); document.write( " $\"+x+%3E+-5.00001+\"$
\n" ); document.write( "It does not pass when
\n" ); document.write( " $\"+x+=+-5+\"$
\n" ); document.write( "Hope this helps\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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