document.write( "Question 115684: I have a test tomorrow and am having a lot of trouble with quadratic equations. i understand some things, but others do not make sense at all. below are 3 problems that i do not understand how to solve. if you could solve the problems and show the steps, that would really help me a lot.\r
\n" ); document.write( "\n" ); document.write( "1. 3x^2 + 9 = 0
\n" ); document.write( "2. 2x^2 - 14x - 10 = 0
\n" ); document.write( "3. -2u^2 + 6 = 3u^2 - 10u\r
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\n" ); document.write( "\n" ); document.write( "i attempted problem one and the answer i ended up with was x = the square root of 3. i thought for those types of problems there were supposed to be two answers though, like x + sq. root three and x equals (another number)
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Algebra.Com's Answer #84186 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
#1\r
\n" ); document.write( "\n" ); document.write( "Well you're forgetting the other part of the answer which is \"x=-sqrt%283%29\". You are correct, there should be two answers.\r
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\n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for x:\r
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\n" ); document.write( "\n" ); document.write( "Starting with the general quadratic\r
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\n" ); document.write( "\n" ); document.write( "\"ax%5E2%2Bbx%2Bc=0\"\r
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\n" ); document.write( "\n" ); document.write( "the general solution using the quadratic equation is:\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29\"\r
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\n" ); document.write( "\n" ); document.write( "So lets solve \"2%2Ax%5E2-14%2Ax-10=0\" ( notice \"a=2\", \"b=-14\", and \"c=-10\")\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28--14+%2B-+sqrt%28+%28-14%29%5E2-4%2A2%2A-10+%29%29%2F%282%2A2%29\" Plug in a=2, b=-14, and c=-10\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2814+%2B-+sqrt%28+%28-14%29%5E2-4%2A2%2A-10+%29%29%2F%282%2A2%29\" Negate -14 to get 14\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2814+%2B-+sqrt%28+196-4%2A2%2A-10+%29%29%2F%282%2A2%29\" Square -14 to get 196 (note: remember when you square -14, you must square the negative as well. This is because \"%28-14%29%5E2=-14%2A-14=196\".)\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2814+%2B-+sqrt%28+196%2B80+%29%29%2F%282%2A2%29\" Multiply \"-4%2A-10%2A2\" to get \"80\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2814+%2B-+sqrt%28+276+%29%29%2F%282%2A2%29\" Combine like terms in the radicand (everything under the square root)\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2814+%2B-+2%2Asqrt%2869%29%29%2F%282%2A2%29\" Simplify the square root (note: If you need help with simplifying the square root, check out this solver)\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2814+%2B-+2%2Asqrt%2869%29%29%2F4\" Multiply 2 and 2 to get 4\r
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\n" ); document.write( "\n" ); document.write( "So now the expression breaks down into two parts\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2814+%2B+2%2Asqrt%2869%29%29%2F4\" or \"x+=+%2814+-+2%2Asqrt%2869%29%29%2F4\"\r
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\n" ); document.write( "\n" ); document.write( "Now break up the fraction\r
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\n" ); document.write( "\n" ); document.write( "\"x=%2B14%2F4%2B2%2Asqrt%2869%29%2F4\" or \"x=%2B14%2F4-2%2Asqrt%2869%29%2F4\"\r
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\n" ); document.write( "\n" ); document.write( "Simplify\r
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\n" ); document.write( "\n" ); document.write( "\"x=7+%2F+2%2Bsqrt%2869%29%2F2\" or \"x=7+%2F+2-sqrt%2869%29%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "So these expressions approximate to\r
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\n" ); document.write( "\n" ); document.write( "\"x=7.65331193145904\" or \"x=-0.653311931459037\"\r
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\n" ); document.write( "\n" ); document.write( "So our solutions are:\r
\n" ); document.write( "\n" ); document.write( "\"x=7.65331193145904\" or \"x=-0.653311931459037\"\r
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\n" ); document.write( "\n" ); document.write( "Notice when we graph \"2%2Ax%5E2-14%2Ax-10\", we get:\r
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\n" ); document.write( "\n" ); document.write( "when we use the root finder feature on a calculator, we find that \"x=7.65331193145904\" and \"x=-0.653311931459037\".So this verifies our answer\r
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\n" ); document.write( "\n" ); document.write( "\"-2u%5E2%2B6=3u%5E2-10u\" Start with the given equation\r
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\n" ); document.write( "\n" ); document.write( "\"-2u%5E2%2B6-3u%5E2%2B10u=0\" Move all of the terms to the left side\r
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\n" ); document.write( "\n" ); document.write( "\"-2u%5E2-3u%5E2%2B10u%2B6=0\" Sort the terms\r
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\n" ); document.write( "\n" ); document.write( "\"-5u%5E2%2B10u%2B6=0\" Combine like terms\r
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\n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for u:\r
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\n" ); document.write( "\n" ); document.write( "Starting with the general quadratic\r
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\n" ); document.write( "\n" ); document.write( "\"au%5E2%2Bbu%2Bc=0\"\r
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\n" ); document.write( "\n" ); document.write( "the general solution using the quadratic equation is:\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29\"\r
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\n" ); document.write( "\n" ); document.write( "So lets solve \"-5%2Au%5E2%2B10%2Au%2B6=0\" ( notice \"a=-5\", \"b=10\", and \"c=6\")\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-10+%2B-+sqrt%28+%2810%29%5E2-4%2A-5%2A6+%29%29%2F%282%2A-5%29\" Plug in a=-5, b=10, and c=6\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-10+%2B-+sqrt%28+100-4%2A-5%2A6+%29%29%2F%282%2A-5%29\" Square 10 to get 100 \r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-10+%2B-+sqrt%28+100%2B120+%29%29%2F%282%2A-5%29\" Multiply \"-4%2A6%2A-5\" to get \"120\"\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-10+%2B-+sqrt%28+220+%29%29%2F%282%2A-5%29\" Combine like terms in the radicand (everything under the square root)\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-10+%2B-+2%2Asqrt%2855%29%29%2F%282%2A-5%29\" Simplify the square root (note: If you need help with simplifying the square root, check out this solver)\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-10+%2B-+2%2Asqrt%2855%29%29%2F-10\" Multiply 2 and -5 to get -10\r
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\n" ); document.write( "\n" ); document.write( "So now the expression breaks down into two parts\r
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\n" ); document.write( "\n" ); document.write( "\"u+=+%28-10+%2B+2%2Asqrt%2855%29%29%2F-10\" or \"u+=+%28-10+-+2%2Asqrt%2855%29%29%2F-10\"\r
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\n" ); document.write( "\n" ); document.write( "Now break up the fraction\r
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\n" ); document.write( "\n" ); document.write( "\"u=-10%2F-10%2B2%2Asqrt%2855%29%2F-10\" or \"u=-10%2F-10-2%2Asqrt%2855%29%2F-10\"\r
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\n" ); document.write( "\n" ); document.write( "Simplify\r
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\n" ); document.write( "\n" ); document.write( "\"u=1-sqrt%2855%29%2F5\" or \"u=1%2Bsqrt%2855%29%2F5\"\r
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\n" ); document.write( "\n" ); document.write( "So these expressions approximate to\r
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\n" ); document.write( "\n" ); document.write( "\"u=-0.483239697419133\" or \"u=2.48323969741913\"\r
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\n" ); document.write( "\n" ); document.write( "So our solutions are:\r
\n" ); document.write( "\n" ); document.write( "\"u=-0.483239697419133\" or \"u=2.48323969741913\"\r
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\n" ); document.write( "\n" ); document.write( "Notice when we graph \"-5%2Ax%5E2%2B10%2Ax%2B6\" (just replace u with x), we get:\r
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\n" ); document.write( "\n" ); document.write( "when we use the root finder feature on a calculator, we find that \"x=-0.483239697419133\" and \"x=2.48323969741913\".So this verifies our answer\r
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