document.write( "Question 852178: 5x^3+30x^2-15x \n" ); document.write( "
Algebra.Com's Answer #513211 by josh_jordan(263)\"\" \"About 
You can put this solution on YOUR website!
In order to solve for x, the first thing you want to do is set this expression equal to 0:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"5x%5E3%2B30x%5E2-15x=0\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Next, since each of these terms have 5x in common, we can factor 5x out of the equation, giving us:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"5x%28x%5E2%2B6x-3%29=0\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Setting each of these terms equal to 0, gives us:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"5x=0\" and \"x%5E2%2B6x-3=0\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "With 5x = 0, we can quickly see that x = 0, so, we know that one of the values of x is 0.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now, in order to find the other two values of x, we need to use the quadratic formula on our second term, x^2 + 6x - 3 = 0:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\" ----->\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-6+%2B-+sqrt%28+6%5E2-4%2A1%2A-3+%29%29%2F%282%2A1%29+\" ----->\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-6+%2B-+sqrt%28+36%2B12+%29%29%2F%282%29+\" ----->\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-6+%2B-+sqrt%28+48+%29%29%2F%282%29+\" ----->\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28-6+%2B-+4%2Asqrt%28+3+%29%29%2F%282%29+\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now, we can factor a 2 out of the numerator, since 2 is a factor of both -6 and +- 4:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%282%28-3+%2B-+2%2Asqrt%28+3+%29%29%29%2F%282%29+\" ----->\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+-3+%2B-+2%2Asqrt%28+3+%29+\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "We now have our 3 values of x: 0,\"-3%2B2%2Asqrt%283%29\",\"-3-2%2Asqrt%283%29\"
\n" ); document.write( "
\n" );