What is the vertex form of #y=9x^2 - 17x - 85 #?

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Answer 1 · 2017-06-08T20:50:24

For the method in detail have a look at:
https://socratic.org/s/aFpc6GYR

#y=9(x-17/18)^2-3349/36#

#y=9(x-17/(2xx9))^2+k-85#

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Note that #" "9(-17/(2xx9))^2+k=0#

#=>17^2/36+k=0#

#=>k=-289/36 =-8 1/36#
.......................................................................

#y=9(x-17/(2xx9))^2-8 1/36-85#

#y=9(x-17/18)^2-3349/36#

Tony B