document.write( "Question 684539: what is the vertex form for:y=-1/3x^2+8/3x-25/3 \n" ); document.write( "
Algebra.Com's Answer #424136 by MathLover1(20849)\"\" \"About 
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the vertex form:\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=%28-1%2F3%29+x%5E2%2B%288%2F3%29+x-25%2F3\" Start with the given equation
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\n" ); document.write( " \"y%2B25%2F3=%28-1%2F3%29+x%5E2%2B%288%2F3%29+x\" Add \"25%2F3\" to both sides
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\n" ); document.write( " \"y%2B25%2F3=%28-1%2F3%29%28x%5E2-8x%29\" Factor out the leading coefficient \"%28-1%2F3%29\"
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\n" ); document.write( " Take half of the x coefficient \"-8\" to get \"-4\" (ie \"%281%2F2%29%28-8%29=-4\").
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\n" ); document.write( " Now square \"-4\" to get \"16\" (ie \"%28-4%29%5E2=%28-4%29%28-4%29=16\")
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\n" ); document.write( " \"y%2B25%2F3=%28-1%2F3%29%28x%5E2-8x%2B16-16%29\" Now add and subtract this value inside the parenthesis. Doing both the addition and subtraction of \"16\" does not change the equation
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\n" ); document.write( " \"y%2B25%2F3=%28-1%2F3%29%28%28x-4%29%5E2-16%29\" Now factor \"x%5E2-8x%2B16\" to get \"%28x-4%29%5E2\"
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\n" ); document.write( " \"y%2B25%2F3=%28-1%2F3%29%28x-4%29%5E2-%28-1%2F3%29%2816%29\" Distribute
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\n" ); document.write( " \"y%2B25%2F3=%28-1%2F3%29%28x-4%29%5E2%2B16%2F3\" Multiply
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\n" ); document.write( " \"y=%28-1%2F3%29%28x-4%29%5E2%2B16%2F3-25%2F3\" Now add \"%2B25%2F3\" to both sides to isolate y
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\n" ); document.write( " \"y=%28-1%2F3%29%28x-4%29%5E2-3\" 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=-1%2F3\", \"h=4\", and \"k=-3\". 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=%28-1%2F3%29x%5E2%2B%288%2F3%29x-25%2F3\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C%28-1%2F3%29x%5E2%2B%288%2F3%29x-25%2F3%29\" Graph of \"y=%28-1%2F3%29x%5E2%2B%288%2F3%29x-25%2F3\". Notice how the vertex is (\"4\",\"-3\").
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\n" ); document.write( " Notice if we graph the final equation \"y=%28-1%2F3%29%28x-4%29%5E2-3\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C%28-1%2F3%29%28x-4%29%5E2-3%29\" Graph of \"y=%28-1%2F3%29%28x-4%29%5E2-3\". Notice how the vertex is also (\"4\",\"-3\").
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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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\n" ); document.write( "\n" ); document.write( "so, (\"h\",\"k\")=(\"4\",\"-3\")
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