document.write( "Question 273318: I need help solving this problem. (x+4)(x-9)=4x \n" ); document.write( "

Algebra.Com's Answer #199689 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"+%28x%2B4%29%28x-9%29=4x\"$
\n" ); document.write( " $\"x%5E2+%2B+4x+-+9x+-+36+-+4x+=+0\"$
\n" ); document.write( " $\"x%5E2+-+9x+-+36+=+0\"$
\n" ); document.write( "Completing the square:
\n" ); document.write( " $\"x%5E2+-+9x+%2B+%289%2F2%29%5E2+=+%289%2F2%29%5E2+%2B+36\"$
\n" ); document.write( " $\"x%5E2+-+9x+%2B+81%2F4+=+81%2F4+%2B+144%2F4\"$
\n" ); document.write( " $\"%28x+-+%289%2F2%29%29%5E2+=+225%2F4\"$
\n" ); document.write( " $\"x+-+9%2F2+=+15%2F2\"$
\n" ); document.write( " $\"x+=+12\"$
\n" ); document.write( "and
\n" ); document.write( " $\"x+-+9%2F2+=+-15%2F2\"$
\n" ); document.write( " $\"x+=+-3\"$
\n" ); document.write( "the solutions are $\"x+=+12\"$ and $\"x+=+-3\"$
\n" ); document.write( "check:
\n" ); document.write( " $\"+%28x%2B4%29%28x-9%29=4x\"$
\n" ); document.write( " $\"%2812%2B4%29%2812-9%29+=+4%2A12\"$
\n" ); document.write( " $\"16%2A3+=+48\"$
\n" ); document.write( " $\"48+=+48\"$
\n" ); document.write( "and
\n" ); document.write( " $\"%28-3%2B4%29%28-3-9%29+=+4%2A%28-3%29\"$
\n" ); document.write( " $\"1%2A%28-12%29+=+-12\"$
\n" ); document.write( " $\"-12+=+-12\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );