What is the vertex form of $y=-9x^2 +12x - 18$ ?

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Answer 1 · 2015-12-26T01:53:47

Below is the proof (a completion of square)

$y = -9x^2 + 12x - 18$

$y = -9(x^2 - 12/9x) - 18$

$y = -9(x^2 - 12/9x +$ _ - _ ) - 18#

$_ = ((-12/9) / 2)^2$

$_ = 4/9$

$y = -9(x^2 - 12/9x + 4/9) - 4/9(-9) - 18$

$y= -9(x - 2/3)^2 - 14$

So, $y = -9x^2 + 12x - 18$ is equal to $y = -9(x - 2/3)^2 - 14$

Hopefully that explanation helped!

What is the vertex form of y=-9x^2 +12x - 18 y=-9x^2 +12x - 18 ?