document.write( "Question 1208061: Given G(x) = -x^4 + 32x + 144,\r
\n" ); document.write( "\n" ); document.write( "A. Determine if G is even, odd,or even.\r
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\n" ); document.write( "\n" ); document.write( "I think I have to evaluate G(-x). Yes? \r
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\n" ); document.write( "\n" ); document.write( "B.There is a local maximum value of 400 at x = 4.
\n" ); document.write( "Determine a second maximum value using a graph.\r
\n" ); document.write( "\n" ); document.write( "Note: DO NOT USE CALCULUS.
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Algebra.Com's Answer #846218 by math_tutor2020(3838)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "Part (a)\r
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\n" ); document.write( "\n" ); document.write( "You can use the method tutor greenestamps mentioned.
  • If all exponents of a polynomial function are even, then the function is even.
  • If all exponents of a polynomial function are odd, then the function is odd.
  • If the polynomial function has a mix of even and odd exponents, then the function is neither even nor odd.
Your polynomial function is
\n" ); document.write( "g(x) = -x^4 + 32x + 144
\n" ); document.write( "which is the same as writing
\n" ); document.write( "g(x) = -x^4 + 32x^1 + 144x^0
\n" ); document.write( "The exponents are 4, 1, and 0. We have a mix of even and odd exponents, so the function is neither even nor odd\r
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\n" ); document.write( "\n" ); document.write( "Another approach for part (a)\r
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\n" ); document.write( "\n" ); document.write( "Recall that:
  • If g(x) = g(-x) for all x in the domain, then g(x) is even.
  • If g(-x) = -g(x) for all x in the domain, then g(x) is odd.
The key thing to focus on here is the \"for all x\".
\n" ); document.write( "If we can find one counterexample, then we'll disprove the claim.\r
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\n" ); document.write( "\n" ); document.write( "Use a calculator, or do so by hand, to determine that
\n" ); document.write( "g(1) = 175
\n" ); document.write( "g(-1) = 111\r
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\n" ); document.write( "\n" ); document.write( "g(1) = g(-1) is false so g(x) = g(-x) isn't true for all x in the domain.
\n" ); document.write( "This means g(x) isn't an even function.\r
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\n" ); document.write( "\n" ); document.write( "g(-1) = -g(1) being false means g(-x) = -g(x) is also false.
\n" ); document.write( "This means g(x) isn't odd.\r
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\n" ); document.write( "\n" ); document.write( "We conclude that g(x) is neither even nor odd\r
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\n" ); document.write( "\n" ); document.write( "If you wanted you can determine these facts
\n" ); document.write( "g(x) = -x^4 + 32x + 144
\n" ); document.write( "g(-x) = -(-x)^4 + 32(-x) + 144
\n" ); document.write( "g(-x) = -x^4 - 32x + 144
\n" ); document.write( "and,
\n" ); document.write( "g(x) = -x^4 + 32x + 144
\n" ); document.write( "-g(x) = -(-x^4 + 32x + 144)
\n" ); document.write( "-g(x) = x^4 - 32x - 144
\n" ); document.write( "Comparing g(x) with g(-x) shows the two functions aren't identical (since the +32x turned into -32x). Therefore, g(x) isn't even.
\n" ); document.write( "Comparing g(-x) with -g(x) shows the two functions aren't identical. Therefore, g(x) isn't odd.
\n" ); document.write( "A graphing calculator can be very useful here.\r
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\n" ); document.write( "\n" ); document.write( "Part (b)\r
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\n" ); document.write( "\n" ); document.write( "There are many graphing options.
\n" ); document.write( "Usually I would turn to GeoGebra, but Desmos is actually the quicker choice when finding the local max.\r
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\n" ); document.write( "\n" ); document.write( "Type the function into Desmos.
\n" ); document.write( "Adjust the window so you can see the highest point.
\n" ); document.write( "The window I'm using is
\n" ); document.write( "xMin = -10
\n" ); document.write( "xMax = 10
\n" ); document.write( "yMin = -300
\n" ); document.write( "yMax = 300
\n" ); document.write( "Other window parameters are possible.
\n" ); document.write( "\"graph%28400%2C400%2C-10%2C11%2C-300%2C329%2C0%2C-x%5E4+%2B+32x+%2B+144%29\"
\n" ); document.write( "The curve is a weird lumpy hill of sorts.
\n" ); document.write( "The curve isn't symmetric, but it somewhat resembles a parabola.\r
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\n" ); document.write( "\n" ); document.write( "To find the highest point simply click anywhere on the curve.
\n" ); document.write( "A small dot at the peak of this curve should show up.
\n" ); document.write( "Click on that highest point to have the coordinates show up.
\n" ); document.write( "You may have to click more than once.\r
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\n" ); document.write( "\n" ); document.write( "The highest point on this curve is at (2,192)
\n" ); document.write( "Therefore, g(x) reaches its max value of 192 when x = 2.\r
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\n" ); document.write( "\n" ); document.write( "I'm not sure why your teacher mentioned \"There is a local maximum value of 400 at x = 4\" when that is false.
\n" ); document.write( "It's possible your teacher made a typo somewhere?
\n" ); document.write( "Note how g(4) = 16 and you can find larger outputs when trying something like g(0) and g(1).
\n" ); document.write( "Also, this curve has one local max only.
\n" ); document.write( "There aren't any neighborhoods we can zoom in on to get another local max.
\n" ); document.write( "The region -infinity < x < 2 is always increasing while 2 < x < infinity is always decreasing.\r
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\n" ); document.write( "\n" ); document.write( "If you want to use GeoGebra, then you'll need to use the function called \"max\". The template is
\n" ); document.write( "max(f, a,b)
\n" ); document.write( "where f is the function and a,b are the endpoints of the interval you are searching.
\n" ); document.write( "One possible thing we could type in would be
\n" ); document.write( "max( -x^4 + 32x + 144, 0, 4)
\n" ); document.write( "The result GeoGebra produces is the point (1.9999999981, 192)
\n" ); document.write( "We get a bit of rounding error. The x coordinate should be exactly 2. \r
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\n" ); document.write( "\n" ); document.write( "If you want to use something like a TI83, then check out this article
\n" ); document.write( "Caution: The \"zoomFit\" feature might be tempting to use, but it's better to type in the xMin,xMax,yMin,yMax values by hand. \r
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\n" ); document.write( "\n" ); document.write( "Want to do this without a graphing calculator? It would take a while, but you can make a table of values.
\n" ); document.write( "It can be done entirely by hand (slowest method) or using a non-graphing calculator (slightly faster but still pretty slow).
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