PreCalc
posted by Zoey .
for the conic y=5x^240x+78 find an equation in standard form and its vertex, focus, and directrix

complete the square
y = 5(x^2  8x + ....) + 78
= 5(x^2  8x + 16  16) + 78
= 5( (x4)^2  16) + 78
= 5(x4)^2  80 + 78
= 5(x4)^2  2
take over .... 
What's my next step??

We could write our answer in the form
y+2 = 5(x4)^2
take a look at
http://jwilson.coe.uga.edu/emt725/class/sarfaty/emt669/instructionalunit/parabolas/parabolas.html
halfway down the page at example 3
and follow the steps. 
thank you!
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