document.write( "Question 164512: Solve the quadratic equation
\n" ); document.write( "4x²+28x-15=0
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Algebra.Com's Answer #121216 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "\"4x%5E2%2B28x-15=0\" Start with the given equation.\r
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\n" ); document.write( "\n" ); document.write( "Notice we have a quadratic equation in the form of \"ax%5E2%2Bbx%2Bc\" where \"a=4\", \"b=28\", and \"c=-15\"\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( "\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4ac+%29%29%2F%282a%29\" Start with the quadratic formula\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-%2828%29+%2B-+sqrt%28+%2828%29%5E2-4%284%29%28-15%29+%29%29%2F%282%284%29%29\" Plug in \"a=4\", \"b=28\", and \"c=-15\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-28+%2B-+sqrt%28+784-4%284%29%28-15%29+%29%29%2F%282%284%29%29\" Square \"28\" to get \"784\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-28+%2B-+sqrt%28+784--240+%29%29%2F%282%284%29%29\" Multiply \"4%284%29%28-15%29\" to get \"-240\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-28+%2B-+sqrt%28+784%2B240+%29%29%2F%282%284%29%29\" Rewrite \"sqrt%28784--240%29\" as \"sqrt%28784%2B240%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-28+%2B-+sqrt%28+1024+%29%29%2F%282%284%29%29\" Add \"784\" to \"240\" to get \"1024\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-28+%2B-+sqrt%28+1024+%29%29%2F%288%29\" Multiply \"2\" and \"4\" to get \"8\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-28+%2B-+32%29%2F%288%29\" Take the square root of \"1024\" to get \"32\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-28+%2B+32%29%2F%288%29\" or \"x+=+%28-28+-+32%29%2F%288%29\" Break up the expression. \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%284%29%2F%288%29\" or \"x+=++%28-60%29%2F%288%29\" Combine like terms. \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+1%2F2\" or \"x+=+-15%2F2\" Simplify. \r
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\n" ); document.write( "\n" ); document.write( "So the answers are \"x+=+1%2F2\" or \"x+=+-15%2F2\" \r
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