Question 2167
I believe you mean -14x^2 + 36x - 30 = 0. Right?  I believe you're the one who asked about the domain & range.
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You can find the vertex and x-intercepts either by "graphing" or by the "complete the square" (CTS) method.  I will do both.
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CTS states that y=a(x-h)^2+k, where (h,k) is the vertex. Noticed the sign of "h" changed.  Always change the sign of h, however, keep the sign of k.  This is how you complete the square.
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First, you have to get the x^2 coefficient to be 1.  To do this we must factor out the -14 from the x terms only (not the -30).
-14(x^2 - 18/7x)-30=0 (36/-14 equals -18/7)
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Now, we have to take half (or divide by 2) of the -18/7 (which is -9/7) and then square that (which is 81/49).  Put the 81/49 in the parentheses, like this:
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-14(x^2 - 18/7x + 81/49) - 30 = 0
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Third we have to multiply 81/49 by the -14 that is factored out (which is -162/7) and then change the sign and put it beside the -30, like this:
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-14(x^2 - 18/7x + 81/49) + 162/7 - 30 = 0
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Fourth, we have to factor the equation inside the parentheses.  Since we have "completed the square", this is real easy to factor.  Just take half of the -18/7 (which is -9/7) and replace this with the -18/7 and then reduce the x^2 to x and square the parentheses.  As well as combined the 162/7 - 30, like this:
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-14(x - 9/7)^2 - 48/7 = 0
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This is now in the form of y = a(x-h)^2 + k, where (h,k) is the vertex.  So the vertex is (9/7, -48/7).  This vertex is the minimum because "a" (which is -14) is a negative.  If it were a positive it would be the maximum.
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To find the x-intercepts, you can graph or simply solve for x (either by factoring or using the quadratic equation).  Since this equation cannot be factored, we must use the quadratic formula: {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
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Plug it in, like this   {{{x = (-36 +- sqrt( 36^2-4*(-14)*(-30) ))/(2*(-14))}}} , which simplifies to be {{{x = (-36 +- sqrt( -384 ))/(-28) }}} 
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I don't know if you know anything about "imaginary/complex numbers" but we will have one.  Since we cannot take the square root of a negative number, there is NO real x-intercepts, only imaginary/complex x-intercepts.  This means it doesn't cross the x-axis at all!
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To find the imaginary/complex intercepts, we can simply the equation more, like this: {{{x = (9/7 + -2i*sqrt(6)/7) }}} 
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<b>So the vertex is (9/7, -48/7) and the x-intercept is {{{x = (9/7 + -2i*sqrt(6)/7) }}}</b>
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Here is the graph to prove my statements:
{{{graph( 400, 200, -2, 3, -11, 3,  -14x^2+36x-30)}}}