document.write( "Question 1049044: solve equation\r
\n" ); document.write( "\n" ); document.write( "3x^3+19x^2-72x=0\r
\n" ); document.write( "\n" ); document.write( "please show steps
\n" ); document.write( "

Algebra.Com's Answer #664638 by josgarithmetic(39617)\"\" \"About 
You can put this solution on YOUR website!
Rational Roots Theorem will give several roots to check using Synthetic Division. Each root found narrows which roots still need to be found.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"72=2%2A36=2%2A6%2A6=2%2A2%2A3%2A6%2A2%2A2%2A3%2A2%2A3=12%2A6\"
\n" ); document.write( "-
\n" ); document.write( "Try to make a list of all combinations of factors for 72.
\n" ); document.write( "\"system%2872=these%2C2%2A36%2C3%2A24%2C4%2A18%2C6%2A12%2C8%2A9%29\"
\n" ); document.write( "Making a full complete list still takes more work because of division by 3 from the leading term.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Try the PLUSes and MINUSES of 2, 3, 4, 6, 8, 9, 12, 18.
\n" ); document.write( "The dividend to use should include all degrees of x less than and equal to 3.... No, not really....
\n" ); document.write( "Why?
\n" ); document.write( "Because you have \"x%283x%5E2%2B19x-72%29=0\".\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "You will NOT REALLY NEED Rational Roots Theorem because you have a function of x multiplied by a quadratic in x. JUST FIND THE ZEROS OF \"highlight_green%283x%5E2%2B19x-72%29\"; you already know that one of your zeros or roots will be x=0.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Roots from the quadratic factor:
\n" ); document.write( "\"%28-19%2B-+sqrt%2819%5E2%2B4%2A3%2A72%29%29%2F2\"
\n" ); document.write( "-
\n" ); document.write( "\"%28-19%2B-+sqrt%281225%29%29%2F2\"
\n" ); document.write( "-
\n" ); document.write( "\"%28-19%2B-+35%29%2F2\"
\n" ); document.write( "-
\n" ); document.write( "-27 and 8\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "--------------------------------------
\n" ); document.write( "--------------------------------------
\n" ); document.write( "The three solutions are \"system%28-27%2C0%2C8%29\"
\n" ); document.write( "--------------------------------------
\n" ); document.write( "--------------------------------------
\n" ); document.write( "
\n" );