document.write( "Question 124681: -3x^2+7x=-5 solve by completing the square. then write in vertex form \n" ); document.write( "
Algebra.Com's Answer #91399 by MathLover1(20850)\"\" \"About 
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\n" ); document.write( "\"-3x%5E2%2B7x=-5\"\r
\n" ); document.write( "\n" ); document.write( "\"-3x%5E2%2B7x+%2B+5+=+0\"\r
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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=-3+x%5E2%2B7+x%2B5\" Start with the given equation
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\n" ); document.write( " \"y-5=-3+x%5E2%2B7+x\" Subtract \"5\" from both sides
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\n" ); document.write( " \"y-5=-3%28x%5E2%2B%28-7%2F3%29x%29\" Factor out the leading coefficient \"-3\"
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\n" ); document.write( " Take half of the x coefficient \"-7%2F3\" to get \"-7%2F6\" (ie \"%281%2F2%29%28-7%2F3%29=-7%2F6\").
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\n" ); document.write( " Now square \"-7%2F6\" to get \"49%2F36\" (ie \"%28-7%2F6%29%5E2=%28-7%2F6%29%28-7%2F6%29=49%2F36\")
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\n" ); document.write( " \"y-5=-3%28x%5E2%2B%28-7%2F3%29x%2B49%2F36-49%2F36%29\" Now add and subtract this value inside the parenthesis. Doing both the addition and subtraction of \"49%2F36\" does not change the equation
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\n" ); document.write( " \"y-5=-3%28%28x-7%2F6%29%5E2-49%2F36%29\" Now factor \"x%5E2%2B%28-7%2F3%29x%2B49%2F36\" to get \"%28x-7%2F6%29%5E2\"
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\n" ); document.write( " \"y-5=-3%28x-7%2F6%29%5E2%2B3%2849%2F36%29\" Distribute
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\n" ); document.write( " \"y-5=-3%28x-7%2F6%29%5E2%2B49%2F12\" Multiply
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\n" ); document.write( " \"y=-3%28x-7%2F6%29%5E2%2B49%2F12%2B5\" Now add \"5\" to both sides to isolate y
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\n" ); document.write( " \"y=-3%28x-7%2F6%29%5E2%2B109%2F12\" 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=-3\", \"h=7%2F6\", and \"k=109%2F12\". 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=-3x%5E2%2B7x%2B5\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C-3x%5E2%2B7x%2B5%29\" Graph of \"y=-3x%5E2%2B7x%2B5\". Notice how the vertex is (\"7%2F6\",\"109%2F12\").
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\n" ); document.write( " Notice if we graph the final equation \"y=-3%28x-7%2F6%29%5E2%2B109%2F12\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C-3%28x-7%2F6%29%5E2%2B109%2F12%29\" Graph of \"y=-3%28x-7%2F6%29%5E2%2B109%2F12\". Notice how the vertex is also (\"7%2F6\",\"109%2F12\").
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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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