Question 1097564
Ok, for a zero at -2, that means you'll have a factor (x + 2)  (its always the opposite sign because the zero 'a' is the value that makes x + a = 0 and that happens at x = -a).   Similarly, for the zero at 2, you have a factor (x-2)...

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Applying this idea to each zero gives you the four factors:
(x + 2)(x - 2)(x - 4)(x-5) =
{{{ (x^2 - 4)(x - 4)(x - 5) }}} = 
{{{ (x^3 - 4x^2 - 4x + 16)(x-5) }}} =
{{{ x^4 -4x^3 - 4x^2 + 16x -5x^3 +20x^2 + 20x - 80 }}} =
{{{ highlight(x^4 -9x^3 +16x^2 + 36x - 80) }}}
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Check:
      x=4:   {{{ 4^4 - 9*4^3 + 16*4^2 + 36*4 - 80 = 256 - 576 + 256 + 144 - 80 = 0 }}}  
      x=2:   {{{ 2^4 - 9*2^3 + 16*2^2 +36*2 - 80 = 16 - 72 + 64 + 72 - 80 = 0 }}}
    and similar for x=-2 and x=5.