document.write( "Question 105112: Good Morning Tutor, \r
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\n" ); document.write( "\n" ); document.write( "x^2 + 7x - 1 = 0 is (-6 +- sqrt of 50 / 2)\r
\n" ); document.write( "\n" ); document.write( "Solve by completeing the square: \r
\n" ); document.write( "\n" ); document.write( "2x^2 + 8x - 5 = 0 is (4 +- sqrt of 26 / 2) \r
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Algebra.Com's Answer #76483 by MathLover1(20849)\"\" \"About 
You can put this solution on YOUR website!

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Solved by pluggable solver: Quadratic Formula
Let's use the quadratic formula to solve for x:

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\n" ); document.write( " Starting with the general quadratic
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\n" ); document.write( " \"ax%5E2%2Bbx%2Bc=0\"
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\n" ); document.write( " the general solution using the quadratic equation is:
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\n" ); document.write( " \"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29\"
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\n" ); document.write( " So lets solve \"x%5E2%2B7%2Ax-1=0\" ( notice \"a=1\", \"b=7\", and \"c=-1\")
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\n" ); document.write( " \"x+=+%28-7+%2B-+sqrt%28+%287%29%5E2-4%2A1%2A-1+%29%29%2F%282%2A1%29\" Plug in a=1, b=7, and c=-1
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\n" ); document.write( " \"x+=+%28-7+%2B-+sqrt%28+49-4%2A1%2A-1+%29%29%2F%282%2A1%29\" Square 7 to get 49
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\n" ); document.write( " \"x+=+%28-7+%2B-+sqrt%28+49%2B4+%29%29%2F%282%2A1%29\" Multiply \"-4%2A-1%2A1\" to get \"4\"
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\n" ); document.write( " \"x+=+%28-7+%2B-+sqrt%28+53+%29%29%2F%282%2A1%29\" Combine like terms in the radicand (everything under the square root)
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\n" ); document.write( " \"x+=+%28-7+%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)
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\n" ); document.write( " \"x+=+%28-7+%2B-+sqrt%2853%29%29%2F2\" Multiply 2 and 1 to get 2
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\n" ); document.write( " So now the expression breaks down into two parts
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\n" ); document.write( " \"x+=+%28-7+%2B+sqrt%2853%29%29%2F2\" or \"x+=+%28-7+-+sqrt%2853%29%29%2F2\"
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\n" ); document.write( " Now break up the fraction
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\n" ); document.write( " \"x=-7%2F2%2Bsqrt%2853%29%2F2\" or \"x=-7%2F2-sqrt%2853%29%2F2\"
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\n" ); document.write( " Simplify
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\n" ); document.write( " \"x=-7%2F2%2Bsqrt%2853%29%2F2\" or \"x=-7%2F2-sqrt%2853%29%2F2\"
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\n" ); document.write( " So the solutions are:
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\n" ); document.write( " \"x=-7%2F2%2Bsqrt%2853%29%2F2\" or \"x=-7%2F2-sqrt%2853%29%2F2\"
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Solved by pluggable solver: Completing the Square to Get a Quadratic into Vertex Form

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\n" ); document.write( " \"y=2+x%5E2%2B8+x-5\" Start with the given equation
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\n" ); document.write( " \"y%2B5=2+x%5E2%2B8+x\" Add \"5\" to both sides
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\n" ); document.write( " \"y%2B5=2%28x%5E2%2B4x%29\" Factor out the leading coefficient \"2\"
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\n" ); document.write( " Take half of the x coefficient \"4\" to get \"2\" (ie \"%281%2F2%29%284%29=2\").
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\n" ); document.write( " Now square \"2\" to get \"4\" (ie \"%282%29%5E2=%282%29%282%29=4\")
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\n" ); document.write( " \"y%2B5=2%28x%5E2%2B4x%2B4-4%29\" Now add and subtract this value inside the parenthesis. Doing both the addition and subtraction of \"4\" does not change the equation
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\n" ); document.write( " \"y%2B5=2%28%28x%2B2%29%5E2-4%29\" Now factor \"x%5E2%2B4x%2B4\" to get \"%28x%2B2%29%5E2\"
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\n" ); document.write( " \"y%2B5=2%28x%2B2%29%5E2-2%284%29\" Distribute
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\n" ); document.write( " \"y%2B5=2%28x%2B2%29%5E2-8\" Multiply
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\n" ); document.write( " \"y=2%28x%2B2%29%5E2-8-5\" Now add \"%2B5\" to both sides to isolate y
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\n" ); document.write( " \"y=2%28x%2B2%29%5E2-13\" Combine like terms
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\n" ); document.write( " Now the quadratic is in vertex form \"y=a%28x-h%29%5E2%2Bk\" where \"a=2\", \"h=-2\", and \"k=-13\". Remember (h,k) is the vertex and \"a\" is the stretch/compression factor.
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\n" ); document.write( " Check:
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\n" ); document.write( " Notice if we graph the original equation \"y=2x%5E2%2B8x-5\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C2x%5E2%2B8x-5%29\" Graph of \"y=2x%5E2%2B8x-5\". Notice how the vertex is (\"-2\",\"-13\").
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\n" ); document.write( " Notice if we graph the final equation \"y=2%28x%2B2%29%5E2-13\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C2%28x%2B2%29%5E2-13%29\" Graph of \"y=2%28x%2B2%29%5E2-13\". Notice how the vertex is also (\"-2\",\"-13\").
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\n" ); document.write( " So if these two equations were graphed on the same coordinate plane, one would overlap another perfectly. So this visually verifies our answer.
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