document.write( "Question 86122: Find the axis of symmetry...
\n" ); document.write( "1. y=-x^2+4x+2
\n" ); document.write( "2. y=x^2+x+1\r
\n" ); document.write( "\n" ); document.write( "Find the x-intercepts...
\n" ); document.write( "1.y=x^2+2x-8
\n" ); document.write( "2. y=x^2-5x-10
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Algebra.Com's Answer #62235 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
1.\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=-1+x%5E2%2B4+x%2B2\" Start with the given equation
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\n" ); document.write( " \"y-2=-1+x%5E2%2B4+x\" Subtract \"2\" from both sides
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\n" ); document.write( " \"y-2=-1%28x%5E2-4x%29\" Factor out the leading coefficient \"-1\"
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\n" ); document.write( " Take half of the x coefficient \"-4\" to get \"-2\" (ie \"%281%2F2%29%28-4%29=-2\").
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\n" ); document.write( " Now square \"-2\" to get \"4\" (ie \"%28-2%29%5E2=%28-2%29%28-2%29=4\")
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\n" ); document.write( " \"y-2=-1%28x%5E2-4x%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-2=-1%28%28x-2%29%5E2-4%29\" Now factor \"x%5E2-4x%2B4\" to get \"%28x-2%29%5E2\"
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\n" ); document.write( " \"y-2=-1%28x-2%29%5E2%2B1%284%29\" Distribute
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\n" ); document.write( " \"y-2=-1%28x-2%29%5E2%2B4\" Multiply
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\n" ); document.write( " \"y=-1%28x-2%29%5E2%2B4%2B2\" Now add \"2\" to both sides to isolate y
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\n" ); document.write( " \"y=-1%28x-2%29%5E2%2B6\" 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\", \"h=2\", and \"k=6\". 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=-1x%5E2%2B4x%2B2\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C-1x%5E2%2B4x%2B2%29\" Graph of \"y=-1x%5E2%2B4x%2B2\". Notice how the vertex is (\"2\",\"6\").
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\n" ); document.write( " Notice if we graph the final equation \"y=-1%28x-2%29%5E2%2B6\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C-1%28x-2%29%5E2%2B6%29\" Graph of \"y=-1%28x-2%29%5E2%2B6\". Notice how the vertex is also (\"2\",\"6\").
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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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Solved by pluggable solver: Completing the Square to Get a Quadratic into Vertex Form

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\n" ); document.write( " \"y=1+x%5E2%2B1+x%2B1\" Start with the given equation
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\n" ); document.write( " \"y-1=1+x%5E2%2B1+x\" Subtract \"1\" from both sides
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\n" ); document.write( " \"y-1=1%28x%5E2%2B1x%29\" Factor out the leading coefficient \"1\"
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\n" ); document.write( "
\n" ); document.write( " Take half of the x coefficient \"1\" to get \"1%2F2\" (ie \"%281%2F2%29%281%29=1%2F2\").
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\n" ); document.write( " Now square \"1%2F2\" to get \"1%2F4\" (ie \"%281%2F2%29%5E2=%281%2F2%29%281%2F2%29=1%2F4\")
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\n" ); document.write( " \"y-1=1%28x%5E2%2B1x%2B1%2F4-1%2F4%29\" Now add and subtract this value inside the parenthesis. Doing both the addition and subtraction of \"1%2F4\" does not change the equation
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\n" ); document.write( " \"y-1=1%28%28x%2B1%2F2%29%5E2-1%2F4%29\" Now factor \"x%5E2%2B1x%2B1%2F4\" to get \"%28x%2B1%2F2%29%5E2\"
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\n" ); document.write( " \"y-1=1%28x%2B1%2F2%29%5E2-1%281%2F4%29\" Distribute
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\n" ); document.write( " \"y-1=1%28x%2B1%2F2%29%5E2-1%2F4\" Multiply
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\n" ); document.write( " \"y=1%28x%2B1%2F2%29%5E2-1%2F4%2B1\" Now add \"1\" to both sides to isolate y
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\n" ); document.write( " \"y=1%28x%2B1%2F2%29%5E2%2B3%2F4\" 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\", \"h=-1%2F2\", and \"k=3%2F4\". 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( "
\n" ); document.write( " Notice if we graph the original equation \"y=1x%5E2%2B1x%2B1\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C1x%5E2%2B1x%2B1%29\" Graph of \"y=1x%5E2%2B1x%2B1\". Notice how the vertex is (\"-1%2F2\",\"3%2F4\").
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\n" ); document.write( " Notice if we graph the final equation \"y=1%28x%2B1%2F2%29%5E2%2B3%2F4\" we get:
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\n" ); document.write( " \"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C1%28x%2B1%2F2%29%5E2%2B3%2F4%29\" Graph of \"y=1%28x%2B1%2F2%29%5E2%2B3%2F4\". Notice how the vertex is also (\"-1%2F2\",\"3%2F4\").
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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( "We can find the x-intercepts by the quadratic formula\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\"\r
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\n" ); document.write( "\n" ); document.write( "the general form of 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 \"x%5E2%2B2%2Ax-8\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-2+%2B-+sqrt%28+%282%29%5E2-4%2A1%2A-8+%29%29%2F%282%2A1%29\" Plug in a=1, b=2, and c=-8\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-2+%2B-+sqrt%28+4-4%2A1%2A-8+%29%29%2F%282%2A1%29\" Square 2 to get 4\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-2+%2B-+sqrt%28+4%2B32+%29%29%2F%282%2A1%29\" Multiply \"-4%2A-8%2A1\" to get \"32\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-2+%2B-+sqrt%28+36+%29%29%2F%282%2A1%29\" Combine like terms in the radicand (everything under the square root)\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-2+%2B-+6%29%2F%282%2A1%29\" Simplify the square root\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-2+%2B-+6%29%2F2\" Multiply 2 and 1 to get 2\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+=+%28-2+%2B+6%29%2F2\" or \"x+=+%28-2+-+6%29%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "Lets look at the first part:\r
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\n" ); document.write( "\n" ); document.write( "\"x=4%2F2\" Add the terms in the numerator\r
\n" ); document.write( "\n" ); document.write( "\"x=2\" Divide\r
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\n" ); document.write( "\n" ); document.write( "So one answer is\r
\n" ); document.write( "\n" ); document.write( "\"x=2\"\r
\n" ); document.write( "\n" ); document.write( "Now lets look at the second part:\r
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\n" ); document.write( "\n" ); document.write( "\"x=-8%2F2\" Subtract the terms in the numerator\r
\n" ); document.write( "\n" ); document.write( "\"x=-4\" Divide\r
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\n" ); document.write( "\n" ); document.write( "So another answer is\r
\n" ); document.write( "\n" ); document.write( "\"x=-4\"\r
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\n" ); document.write( "\n" ); document.write( "So our solutions are:\r
\n" ); document.write( "\n" ); document.write( "\"x=2\" or \"x=-4\"\r
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\n" ); document.write( "\n" ); document.write( "Notice when we graph \"x%5E2%2B2%2Ax-8\" we get:\r
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\n" ); document.write( "\n" ); document.write( "\"+graph%28+500%2C+500%2C+-14%2C+12%2C+-14%2C+12%2C1%2Ax%5E2%2B2%2Ax%2B-8%29+\"\r
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\n" ); document.write( "\n" ); document.write( "and we can see that the roots are \"x=2\" and \"x=-4\". This verifies our answer\r
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\n" ); document.write( "\n" ); document.write( "2.\r
\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\"\r
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\n" ); document.write( "\n" ); document.write( "the general form of 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 \"x%5E2-5%2Ax-10\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%285+%2B-+sqrt%28+%28-5%29%5E2-4%2A1%2A-10+%29%29%2F%282%2A1%29\" Plug in a=1, b=-5, and c=-10\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%285+%2B-+sqrt%28+25-4%2A1%2A-10+%29%29%2F%282%2A1%29\" Square -5 to get 25\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%285+%2B-+sqrt%28+25%2B40+%29%29%2F%282%2A1%29\" Multiply \"-4%2A-10%2A1\" to get \"40\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%285+%2B-+sqrt%28+65+%29%29%2F%282%2A1%29\" Combine like terms in the radicand (everything under the square root)\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%285+%2B-+sqrt%2865%29%29%2F%282%2A1%29\" Simplify the square root\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%285+%2B-+sqrt%2865%29%29%2F2\" Multiply 2 and 1 to get 2\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+=+%285+%2B+sqrt%2865%29%29%2F2\" or \"x+=+%285+-+sqrt%2865%29%29%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "Which approximate to\r
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\n" ); document.write( "\n" ); document.write( "\"x=6.53112887414927\" or \"x=-1.53112887414927\"\r
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\n" ); document.write( "\n" ); document.write( "So our solutions are:\r
\n" ); document.write( "\n" ); document.write( "\"x=6.53112887414927\" or \"x=-1.53112887414927\"\r
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\n" ); document.write( "\n" ); document.write( "Notice when we graph \"x%5E2-5%2Ax-10\" we get:\r
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\n" ); document.write( "\n" ); document.write( "when we use the root finder feature on our calculator, we find that \"x=6.53112887414927\" and \"x=-1.53112887414927\".So this verifies our answer
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