How do you write the quadratic in vertex form given y=-3x^2-24x+7y=−3x2−24x+7?

1 Answer
Nghi N.
May 10, 2015

Coordinates of vertex :

x = -b/(2a) = 24/-6 = -4x=−b2a=24−6=−4

y = f(-b/2a) = f(-4) = -3(16) - 24(-4) + 7 = -48 + 96 + 7 = 55

Vertex form: y = -3.(x + 4)^2 + 55y=−3.(x+4)2+55

Check:

Develop: -3(x + 4)^2 + 55 = -3.(x^2 + 8x + 16) + 55Develop:−3(x+4)2+55=−3.(x2+8x+16)+55 =
= -3x^2 - 24x - 48 + 55 = -3x^2 - 24x + 7. =−3x2−24x−48+55=−3x2−24x+7. Correct

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