document.write( "Question 122759: Solve.\r
\n" ); document.write( "\n" ); document.write( "(1)x squared - 7x - 1 = 0\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "(2)x squared - 4x - 4 = 0\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "(3)6x squared = 9x
\n" ); document.write( "

Algebra.Com's Answer #90122 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
# 1\r
\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%5E2-7%2Ax-1=0\" ( notice \"a=1\", \"b=-7\", and \"c=-1\")\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%28--7+%2B-+sqrt%28+%28-7%29%5E2-4%2A1%2A-1+%29%29%2F%282%2A1%29\" Plug in a=1, b=-7, and c=-1\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%287+%2B-+sqrt%28+%28-7%29%5E2-4%2A1%2A-1+%29%29%2F%282%2A1%29\" Negate -7 to get 7\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%287+%2B-+sqrt%28+49-4%2A1%2A-1+%29%29%2F%282%2A1%29\" Square -7 to get 49 (note: remember when you square -7, you must square the negative as well. This is because \"%28-7%29%5E2=-7%2A-7=49\".)\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%287+%2B-+sqrt%28+49%2B4+%29%29%2F%282%2A1%29\" Multiply \"-4%2A-1%2A1\" to get \"4\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%287+%2B-+sqrt%28+53+%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+=+%287+%2B-+sqrt%2853%29%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+=+%287+%2B-+sqrt%2853%29%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+=+%287+%2B+sqrt%2853%29%29%2F2\" or \"x+=+%287+-+sqrt%2853%29%29%2F2\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now break up the fraction\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=%2B7%2F2%2Bsqrt%2853%29%2F2\" or \"x=%2B7%2F2-sqrt%2853%29%2F2\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Simplify\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=7+%2F+2%2Bsqrt%2853%29%2F2\" or \"x=7+%2F+2-sqrt%2853%29%2F2\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So these expressions approximate to\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=7.14005494464026\" or \"x=-0.140054944640259\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So our solutions are:\r
\n" ); document.write( "\n" ); document.write( "\"x=7.14005494464026\" or \"x=-0.140054944640259\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Notice when we graph \"x%5E2-7%2Ax-1\", we get:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "when we use the root finder feature on a calculator, we find that \"x=7.14005494464026\" and \"x=-0.140054944640259\".So this verifies our answer\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "
\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "# 2\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-4=0\" ( notice \"a=1\", \"b=-4\", and \"c=-4\")\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-4+%29%29%2F%282%2A1%29\" Plug in a=1, b=-4, and c=-4\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-4+%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-4+%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%2B16+%29%29%2F%282%2A1%29\" Multiply \"-4%2A-4%2A1\" to get \"16\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x+=+%284+%2B-+sqrt%28+32+%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-+4%2Asqrt%282%29%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-+4%2Asqrt%282%29%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+4%2Asqrt%282%29%29%2F2\" or \"x+=+%284+-+4%2Asqrt%282%29%29%2F2\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now break up the fraction\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=%2B4%2F2%2B4%2Asqrt%282%29%2F2\" or \"x=%2B4%2F2-4%2Asqrt%282%29%2F2\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Simplify\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=2%2B2%2Asqrt%282%29\" or \"x=2-2%2Asqrt%282%29\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So these expressions approximate to\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=4.82842712474619\" or \"x=-0.82842712474619\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So our solutions are:\r
\n" ); document.write( "\n" ); document.write( "\"x=4.82842712474619\" or \"x=-0.82842712474619\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Notice when we graph \"x%5E2-4%2Ax-4\", we get:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "when we use the root finder feature on a calculator, we find that \"x=4.82842712474619\" and \"x=-0.82842712474619\".So this verifies our answer\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "
\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "# 3\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"6x%5E2=9x\" Start with the given equation\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"6x%5E2-9x=0\" Subtract 9x from both sides\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"3x%282x-3%29=0\" Factor the left side \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now set each factor equal to zero:\r
\n" ); document.write( "\n" ); document.write( "\"3x=0\" or \"2x-3=0\" \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"x=0\" or \"x=3%2F2\" Now solve for x in each case\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So our answer is \r
\n" ); document.write( "\n" ); document.write( " \"x=0\" or \"x=3%2F2\" \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Notice if we graph \"y=6x%5E2-9x\" we can see that the roots are \"x=0\" and \"x=3%2F2\" . So this visually verifies our answer.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"+graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C0%2C+6x%5E2-9x%29+\"
\n" ); document.write( "
\n" );