document.write( "Question 137329: The square root of 5x+21=x+3...what is x and how did you figure it out? \n" ); document.write( "

Algebra.Com's Answer #100478 by Fombitz(32388) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"sqrt%285x%2B21%29=x%2B3\"$
\n" ); document.write( "First step, square both sides to get rid of the radical.
\n" ); document.write( " $\"5x%2B21=%28x%2B3%29%5E2\"$
\n" ); document.write( "Expand the right hand side.
\n" ); document.write( " $\"5x%2B21=x%5E2%2B6x%2B9\"$
\n" ); document.write( "Bring all terms over to the left hand side.
\n" ); document.write( " $\"5x%2B21-x%5E2-6x-9=0\"$
\n" ); document.write( " $\"-x%5E2-x%2B12=0\"$
\n" ); document.write( "Multiply both sides by -1.
\n" ); document.write( " $\"x%5E2%2Bx-12=0\"$
\n" ); document.write( "Factor your quadratic equation.
\n" ); document.write( " $\"%28x%2B4%29%28x-3%29=0\"$
\n" ); document.write( "x=-4 and x=3 are both solutions.
\n" ); document.write( "Check your answers.
\n" ); document.write( "x=3
\n" ); document.write( " $\"sqrt%285x%2B21%29=x%2B3\"$
\n" ); document.write( " $\"sqrt%285%283%29%2B21%29=3%2B3\"$
\n" ); document.write( " $\"sqrt%2815%2B21%29=6\"$
\n" ); document.write( " $\"sqrt%2836%29=6\"$
\n" ); document.write( " $\"6=6\"$
\n" ); document.write( "True statement. Good answer.
\n" ); document.write( "x=-4
\n" ); document.write( " $\"sqrt%285%28-4%29%2B21%29=-4%2B3\"$
\n" ); document.write( " $\"sqrt%28-20%2B21%29=-1\"$
\n" ); document.write( " $\"sqrt%281%29=-1\"$
\n" ); document.write( "True statement, since $\"%28-1%29%5E2=1\"$ .
\n" ); document.write( "Good answer.
\n" ); document.write( " \n" ); document.write( "

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