What is the vertex of #y=-2x^2+8x-12 #?

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Answer 1 · 2016-01-26T13:23:39

#x_("vertex")=2# ...I will let you find y by substitution

This is a real cool trick

Given: #y=-2x^2+8x-12#

Write as #y=-2(x^2-8/2x)-12#

Consider the #-8/2 " from " -8/2x#

Apply this process: #(-1/2)xx(-8/2) = + 8/4=2#

#x_("vertex")=2#

You can see that this is true from the graph

Now all you have to do is substitute for x in the original equation to find y.

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