document.write( "Question 102555This question is from textbook Algebra and Trigonometry
\n" ); document.write( ": Find the solutions to the equation x-5/x= 4. \n" ); document.write( "
Algebra.Com's Answer #74577 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
\"x-5%2Fx=+4\" Start with the given equation\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x%5E2-5=+4x\" Multiply both sides by the LCD x\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x%5E2-4x-5=0+\" Subtract 4x from both sides\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for x:\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Starting with the general quadratic\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"ax%5E2%2Bbx%2Bc=0\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "the general solution using the quadratic equation is:\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( "
\n" ); document.write( "\n" ); document.write( "So lets solve \"x%5E2-4%2Ax-5=0\" ( notice \"a=1\", \"b=-4\", and \"c=-5\")\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28--4+%2B-+sqrt%28+%28-4%29%5E2-4%2A1%2A-5+%29%29%2F%282%2A1%29\" Plug in a=1, b=-4, and c=-5\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%284+%2B-+sqrt%28+%28-4%29%5E2-4%2A1%2A-5+%29%29%2F%282%2A1%29\" Negate -4 to get 4\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%284+%2B-+sqrt%28+16-4%2A1%2A-5+%29%29%2F%282%2A1%29\" Square -4 to get 16 (note: remember when you square -4, you must square the negative as well. This is because \"%28-4%29%5E2=-4%2A-4=16\".)\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%284+%2B-+sqrt%28+16%2B20+%29%29%2F%282%2A1%29\" Multiply \"-4%2A-5%2A1\" to get \"20\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%284+%2B-+sqrt%28+36+%29%29%2F%282%2A1%29\" Combine like terms in the radicand (everything under the square root)\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%284+%2B-+6%29%2F%282%2A1%29\" Simplify the square root (note: If you need help with simplifying the square root, check out this solver)\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%284+%2B-+6%29%2F2\" Multiply 2 and 1 to get 2\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So now the expression breaks down into two parts\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%284+%2B+6%29%2F2\" or \"x+=+%284+-+6%29%2F2\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Lets look at the first part:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=%284+%2B+6%29%2F2\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=10%2F2\" Add the terms in the numerator\r
\n" ); document.write( "\n" ); document.write( "\"x=5\" Divide\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So one answer is\r
\n" ); document.write( "\n" ); document.write( "\"x=5\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now lets look at the second part:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=%284+-+6%29%2F2\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=-2%2F2\" Subtract the terms in the numerator\r
\n" ); document.write( "\n" ); document.write( "\"x=-1\" Divide\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So another answer is\r
\n" ); document.write( "\n" ); document.write( "\"x=-1\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So our solutions are:\r
\n" ); document.write( "\n" ); document.write( "\"x=5\" or \"x=-1\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Notice when we graph \"x%5E2-4%2Ax-5\", we get:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"+graph%28+500%2C+500%2C+-11%2C+15%2C+-11%2C+15%2C1%2Ax%5E2%2B-4%2Ax%2B-5%29+\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "and we can see that the roots are \"x=5\" and \"x=-1\". This verifies our answer
\n" ); document.write( "
\n" ); document.write( "
\n" );