Question 84352
There are several ways that you can find the value of x that represents the axis of symmetry.
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One of these ways is to get the quadratic equation in the form that you need to apply the
quadratic formula.  That form is:
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{{{ax^2 + bx + c}}}
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Then recognize that the axis of symmetry is determined by that term of the of the answer to
the quadratic equation that is:
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 {{{-b/(2*a)}}}
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In this case, by comparing the quadratic expression of the problem:
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{{{x^2-x-8}}}
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with the standard quadratic form:
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{{{ax^2 + bx + c}}}
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you can see that a = 1, b = -1, and c = -8.  Substitute the appropriate values here into:
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{{{-b/(2*a)}}}
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and you get:
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{{{-(-1)/(2*1) = 1/2 }}}
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So the answer to this problem is that the equation for the line of symmetry is:
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{{{x = 1/2}}}
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Hope that this clarifies the significance of the first term in the quadratic formula:
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{{{x = -b/2a +- (sqrt( b^2-4*a*c ))/(2*a) }}} 
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It is the axis of symmetry about which the answers are equally spaced in both the + and
the - directions.
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